The Parisian custard tart: a thick, sliceable vanilla custard — thickened with cornstarch and set by eggs — poured hot into a raw pâte brisée shell and baked hot for a dark, blistered top. The custard is a one-pot pastry cream (everything whisked cold and boiled, no tempering), then baked, then chilled overnight. Sized for an 8-inch × 2-inch tart ring.

Ingredients

   
  Pâte brisée
200g all-purpose flour
100g cold unsalted butter, cubed
1 egg yolk
40g ice water
3g salt
  Custard
860g whole milk
100g whole egg (~2 large)
36g egg yolk (~2 yolks)
100g sugar
50g cornstarch
10g vanilla bean paste (or 2 vanilla beans, split and scraped — see notes)
  pinch of salt

Steps

  1. Pâte brisée: rub the cold butter into the flour and salt until sandy with some pea-sized bits. Mix the yolk into the ice water, add, and bring together into a dough — don’t overwork. Flatten, wrap, and chill at least 1 hour.

  2. Roll the dough 2–3mm thick. Set the 8×2-inch ring on a parchment-lined baking sheet and line it — base and full tall sides — pressing into the corner and leaving a slight overhang. Dock the base with a fork. Freeze the lined shell hard, at least 30 minutes (no blind-baking needed — see notes). Preheat the oven to 400°F.

  3. Custard (one pot, no tempering): in a saucepan off the heat, whisk the milk, eggs, yolks, sugar, cornstarch, vanilla, and salt together cold until completely smooth with no cornstarch streaks. (Using beans instead of paste? Scrape in the seeds and drop in the split pods too — fish the pods out before pouring.)

  4. Set over medium heat and whisk constantly, scraping the bottom and corners with a spatula, until it thickens and comes to a full boil — let it bubble 1–2 minutes, whisking hard, until thick and glossy (~200°F). Boiling is essential: it sets the starch and denatures the yolks’ amylase, or the custard turns runny later. For insurance, pass it through a sieve.

  5. Pour the hot custard straight onto the frozen shell, filling to ~1cm below the rim. Smooth the top. (Pouring it hot sets the base fast — part of why the raw shell doesn’t go soggy.)

  6. Bake at 400°F for 15 minutes to blister the top, then drop to 350°F and bake 40–55 minutes more, until the top is deeply browned (even a little scorched) and the center wobbles like set jelly. Tent with foil if the top darkens too fast.

  7. Cool completely (~2 hours), then refrigerate at least 4 hours, ideally overnight. Run a knife around the ring and lift it off. Serve cold. Best the next day.

Analysis

Total custard: 1046g (pâte brisée shell excluded)

Component Amount % of custard
Structure solids (cornstarch) 50g 4.8%
Fat (milk, egg, yolk) 49g 4.6%
Sugar (added + lactose) 137g 13.0%
Liquid (milk and egg water) 768g 73.4%
Egg/milk protein 43g 4.1%

A starch-and-egg set, which is the whole point: unlike a pure egg-set purin (baked gently in a water bath and spoonable), the ~5% cornstarch is what lets this slice into clean wedges. The starch also protects the eggs — its granules block the egg proteins from cross-linking, so the custard can be boiled on the stove without curdling. It’s boiled deliberately: egg yolks carry amylase, a starch-digesting enzyme, and only a full boil kills it — skip that and the starch is quietly digested as it cools and the flan slumps. Sugar reads modest (~13%) because there’s no fruit bringing its own, just milk and added sugar.

Notes

  • Boil the custard — really boil it. The single most important step, and the one thing laziness can’t touch. It has to reach a full, glossy, bubbling boil for 1–2 minutes so the yolks’ amylase is denatured; stop at “thick” without boiling and the enzyme keeps digesting the starch as it cools, and the flan sets runny. Whisk constantly and scrape the corners so the bottom doesn’t scorch.
  • The one-pot method is the lazy way, and it’s genuinely as good. Whisking everything cold and heating it together skips tempering entirely — tempering only exists to keep hot milk from scrambling raw egg, and here nothing starts hot. The cornstarch and sugar shield the egg proteins so it can boil without curdling (Stella Parks endorses exactly this). Since the flan bakes again, it’s the most forgiving pastry cream there is. The only care points: whisk on medium (not high) so it doesn’t scorch, and sieve it after as cheap insurance against lumps.
  • Real vanilla bean, still one pot. You don’t need a separate steep to use a bean — the one-pot mix comes to a boil anyway, so just split and scrape 2 beans (seeds and pods) straight into the cold pot with everything else, heat, and fish out the pods before pouring (or let the sieve catch them). The seeds carry the flecks and most of the flavor and release fully. A dedicated 15-min hot steep pulls a little more out of the woody pods, but it means heating the milk separately and tempering — not worth it here. For a touch more, leave the pods in while the custard cools, then strain. Vanilla paste is the zero-effort route at ~90% of the flavor.
  • Cornstarch, not flour. Cornstarch gives the smooth, dense, clean-slicing set; flour would taste pasty and cloud it. This isn’t a clafoutis/far breton batter — it’s a pastry cream that happens to be baked.
  • No par-baking — but freeze the shell. A pre-cooked pastry cream carries little free water (the cornstarch locks it into a gel), so it doesn’t soak into the crust the way a thin raw liquid does in a quiche or crème caramel — and a long, hot bake cooks the raw base through. This is how nearly every French brisée and sucrée flan is made (Conticini, Lignac, Empreinte Sucrée). The three things that keep the raw base from going soggy: freeze the lined shell hard before filling (also stops the tall walls slumping), pour the custard in hot (sets the base fast), and use the metal ring (conducts bottom heat — the rare soggy failures happen in insulating ceramic dishes). If you’d rather have insurance — a cooler oven, a ceramic dish, or you just want a crisper base — blind-bake the frozen shell at 425°F for 25 min with weights, then 5 min uncovered, before filling.
  • The dark top is the signature — chase it. Flan parisien wants a deeply browned, blistered, almost-burnt top, which is why it starts hot. If yours is going pale, push the initial heat or hit it under the broiler for a minute at the end. A blonde top tastes underdone.
  • Wobble, then chill — don’t overbake. Pull it while the center still jiggles like set jelly; it firms entirely on cooling. Bake until the middle is firm and it’ll crack, dome, and sink. The overnight chill is not optional — slice it warm and the center runs.
  • Tart ring. The 8×2-inch ring is bottomless — it sits directly on the parchment so the base crisps against the tray. Lift the ring off after baking once the crust has set.
  • All-milk is the classic, and it’s rich enough. Traditional flan parisien uses no cream (Conticini’s is famously milk-only) — the richness comes from the egg yolks (fat + lecithin) and the ~5% cornstarch body, concentrated by the long bake. Cream isn’t needed.
  • Richer version, if you want it. Replace ~100–170g of the milk with heavy cream (up to ~20% of the dairy) for a fuller, silkier custard — a ~150g splash roughly doubles the fat. Don’t go past ~20%: cream fat inhibits the starch set, so more than that softens the slice toward a loose custard tart (add an extra yolk to protect the slice if you push it). Or whisk 100–120g mascarpone into the finished custard (Grolet-style) — its low free water enriches without softening the set as much as pourable cream, and push the vanilla up to match.
  • Make-ahead. This is a next-day dessert by design — the flavor and set are both better after a night in the fridge. Keeps 3–4 days refrigerated.
  • Related custards on this site: Purin (pure egg-set, no starch), Black Tea Pudding, and the Cream in Custards article.