Prep the Pan: Preheat the oven to 350°F (177°C) with the rack in the middle position. Brush only the bottom of a 10-inch springform pan with unsalted butter. Add 3 Tablespoons of all-purpose flour, tap it around to cover the bottom surface, then flip the pan over and tap out the excess. Do not grease the sides!
Whip the Egg Whites: In a perfectly clean stand mixer bowl with a whisk attachment, whip the room-temperature egg whites on high speed to soft peaks. Add the cream of tartar and continue whipping until stiff peaks form. Transfer the whites to a separate bowl and set aside.
Mix the Batter Base: In the stand mixer with a paddle attachment, mix the egg yolks, white sugar, and vanilla sugar on medium speed for about 5 minutes until the sugar dissolves and the mixture doubles in volume. Add the softened butter and mix until combined.
Add Dry Ingredients and Fold: In a separate bowl, whisk together the flour, cornstarch, baking powder, and salt. With the mixer on low speed, add the dry mixture ½ cup at a time, mixing only until just combined. Remove the bowl from the mixer. Add half of the whipped egg whites to the batter and gently fold with a spatula until just combined. Add the remaining whites and fold gently. Do not overmix!
Bake and Trim: Pour the batter into the springform pan, smooth the surface, and tap the pan on the counter to release air bubbles. Bake for 25 minutes, or until a toothpick inserted into the center comes out clean. Let cool completely. If the cake baked with a dome, remove the springform ring, use a serrated knife to trim the top flat, and replace the ring tightly around the cake.
Assemble the Cake: Stir the chilled vanilla pudding until smooth, then spread it evenly over the flat top of the cake. Decorate by placing the halved strawberries in a circular pattern, starting from the outside edge and working your way into the center.
Glaze and Chill: Follow the package instructions to cook the red glaze. Working quickly, use a ladle to pour the hot glaze evenly over the strawberries. Let the glaze set (it takes only minutes). Serve immediately, or chill in the refrigerator for 30 minutes to 1 hour before slicing. Store leftovers in an airtight container in the fridge for up to 5 days.