Prep the bread and pan: If your brioche is fresh, leave the slices uncovered on a wire rack for 30–60 minutes to dry slightly (or toast briefly). Slightly stale / day-old bread soaks up the custard without collapsing — that's what gives French toast its custardy center and intact shape. Arrange a large skillet or heavy nonstick pan near the stove; you'll want it hot and ready.

Make the custard batter: In a wide, shallow dish (a rimmed baking sheet or pie dish works well) whisk together the eggs, whole milk, granulated sugar, vanilla extract, ground cinnamon and sea salt until completely smooth and slightly frothy. Whisking incorporates air for a lighter custard and ensures the sugar dissolves — this helps the mixture coat the bread evenly.

Melt and brown part of the butter: In your skillet melt 1 tablespoon of the butter over medium heat and allow it to foam and just start to turn a light golden-brown (about 2 minutes). Browning the butter concentrates nutty, caramel notes that give the finished toast a deeper, restaurant-style flavor. Watch carefully — brown butter can go from nutty to burnt in seconds. Remove skillet from heat for a moment and set aside (we'll use the rest of the butter later for basting).

Soak the bread briefly: Working one slice at a time, lay a slice brioche in the custard for 10–20 seconds per side — just long enough for the interior to absorb some custard but not so long the slice becomes saturated and falls apart. For very thick slices (1 to 1 1/2 inches) use the full 20 seconds per side; for thinner slices aim for 10–12 seconds. Press gently so the custard penetrates the crumb — but avoid squeezing out the custard, which will make the bread soggy.

Pan-fry to develop a golden crust: Return the skillet with the browned butter to medium heat, add the remaining 1 tablespoon butter (or the remaining divided butter so there is about 2 tbsp melted in the pan total) and swirl to coat. Add the soaked slices (don’t overcrowd — do 3–4 slices at a time depending on pan size). Cook 2.5–3 minutes per side, undisturbed, until deep golden-brown and caramelized. Cooking undisturbed lets a crust form; flipping too soon prevents browning and encourages the toast to tear.

Finish in the oven if necessary: If using very thick slices and the centers feel undercooked after browning, set the skillet in a preheated 350°F (175°C) oven for 3–5 minutes to finish cooking through without burning the exterior. The oven ensures the center becomes custardy and fully set while preserving the browned crust.

Rest briefly and dress: Transfer cooked French toast to a wire rack or warm plate for 1–2 minutes — this lets the custard settle and keeps the crust crisp. Serve immediately with 1 tablespoon of pure maple syrup per serving. Optionally dust with powdered sugar, add fresh berries or a pat of butter.

Plating suggestion (restaurant-style): Stack two slices at the center of a warmed plate, angle a third small piece or toasted brioche crust against them for height, drizzle warm maple syrup along one side, and finish with a few micro-herbs or a scattering of berries for color. The contrast of a hot, caramelized edge and a tender, silky interior is the hallmark of great pain perdu.