Whisk the sugar, cornstarch and salt together. Whisk in the egg yolks until pale and smooth, about 1 minute. Bring the milk to a simmer, remove it from the heat, and slowly whisk it into the yolk mixture. Return the mixture to the saucepan and cook over medium heat until it begins to bubble, then cook 1 more minute. Stir in the vanilla, strain into a bowl, and cover with plastic wrap directly on the surface. Refrigerate until cool.

Mix the yeast and warm milk in a stand mixer bowl. The yeast should begin to foam after a few minutes. Mix in the eggs, sugar, honey and salt, then add the flour. With the mixer running, add the softened butter a little at a time. Knead until smooth and elastic, approximately 6 minutes.

Cover the bowl and leave it in a warm place for 1 hour, or until the dough has doubled in size.

Butter the bottom and sides of a 9-inch cake pan at least 2 inches deep. Gently shape the dough into a circle that fits the pan. Cover and let rise for 30 minutes.

Combine the butter, honey, sugar and cream in a saucepan. Bring to a boil over medium-high heat and cook for 2 to 3 minutes, until light golden. Remove from the heat, stir in the sliced almonds, and let cool slightly. Heat the oven to 350°F.

Spread the honey-almond topping evenly over the dough. Bake for 25 to 30 minutes, until the edges are golden and the topping is bubbling.

Cool in the pan for 20 minutes so the topping can firm up. Loosen the edges with a knife, remove the cake from the pan, and cool completely on a rack with the almonds facing up. Split the cake horizontally with a serrated knife.

Whip the heavy cream to soft peaks. Whisk the chilled pastry cream until smooth, about 1 minute, then gently fold in the whipped cream. Spread the filling over the bottom cake layer and replace the top layer, almond side up.