Make the Soufflé Pancake Cake Recipe for a cloud-like dessert; bake gently, top with whipped cream and fresh berries.
Preheat the oven to 300°F (150°C) and position a rack in the lower-middle so the cake can rise without touching the oven top. Grease the bottom and sides of a 7-inch (18 cm) round cake pan (or springform) with a thin layer of butter, line the bottom with a round of parchment, and fit a tall parchment collar that extends 1–2 inches above the rim; lightly grease the parchment as well. Place that prepared cake pan inside a larger deep roasting pan with at least 1 inch (2.5 cm) of clearance all around so water can circulate later. Keep a clean offset spatula nearby for smoothing.

Whisk together the cake flour, cornstarch and fine sea salt in a small bowl, then pass them through a fine sieve so the mixture is airy and lump-free; set this sifted dry mix within reach. This is a light, powdery, snow-like pile with a faint, matte texture that will give the final cake its delicate crumb.
In a modern matte grey mixing bowl, whisk the 4 egg yolks together with the 20 g sugar until the color lightens and the texture becomes creamy and slightly thickened. Add the whole milk, vanilla and the warm, slightly cooled melted butter and whisk until fully combined into a pale, satin-smooth batter with a few faint whisk ribbons and no lumps. The batter should be thick but still pourable.

Using a clean glass mixing bowl, begin beating the egg whites with the cream of tartar until foamy, then gradually add the 60 g sugar while increasing speed. Stop when the meringue is glossy with soft–to–medium peaks—peaks that stand but gently bend at the tip—showing a mirror-like sheen and a tender, marshmallow-like texture. Rest the whisk on the rim so its wires catch a few silky folds.

Transfer about one-third of the meringue to the matte grey bowl of yolk batter to lighten it, then fold the remaining meringue in two gentle additions. Use broad, sweeping folds that cut through the center and lift from the bottom, turning the bowl as you go. The result is an airy, pale batter that holds soft peaks, thick and cloud-like with tiny suspended air pockets—light enough to barely wobble on the spatula. Carefully pour and scrape this aerated batter into the prepared parchment-lined round pan, smooth the top, tap gently to release major bubbles and run a skewer in a soft spiral if needed. A neutral matte spatula rests on the rim.

Place the filled cake pan into the larger roasting pan, bring very hot water to a near simmer, and carefully pour the hot water around the cake pan until it reaches about halfway up the sides (no splashes into the batter). Slide the roasting pan into the preheated oven and bake at 300°F (150°C) for 45–55 minutes until the top is a very light golden color, edges look set, and the center springs back gently. After baking, turn off the oven and crack the door to let the cake rest 10–15 minutes, then remove the cake pan from the water bath and cool on a wire rack, running a thin knife around the parchment so it peels away cleanly.
Chill a medium bowl and combine the heavy cream, powdered sugar and vanilla, then whip to soft–to–medium peaks—smooth, billowy cream that holds shape but still looks pillowy and moist. Keep the cream airy and not overbeaten so it remains glossy and spreadable for a light finish.
Remove the outer ring if using a springform or invert carefully to keep the top side up; peel away the parchment. Dust the warm or room-temperature soufflé pancake cake lightly with powdered sugar, spread or pipe the whipped cream in billowy mounds, arrange a mix of fresh berries on top (sliced strawberries, blueberries, raspberries), and optionally drizzle a little pure maple syrup at the edge of each slice. Serve immediately while the interior is tender, slightly jiggly and cloud-like.
