Step 1: In a small bowl, warm the milk to about 105-115°F (40-46°C). Sprinkle yeast and 1 teaspoon of the sugar over the milk. Let it sit for 5-10 minutes until foamy, indicating the yeast is active.
Step 2: In a large mixing bowl, combine the flour, remaining sugar, and salt. Make a well in the center.
Step 3: Add the melted butter, egg, and activated yeast mixture to the well. Mix with a wooden spoon or a stand mixer with a dough hook until a shaggy dough forms.
Step 4: Turn the dough out onto a lightly floured surface and knead for 8-10 minutes until smooth and elastic.
Step 5: Place the dough in a lightly oiled bowl, turn once to coat, cover, and let rise in a warm place for 1-1.5 hours, or until doubled in size.
Step 6: While the dough rises, prepare the almond topping. In a saucepan, melt 1/2 cup butter over medium heat. Add 1/2 cup sugar, honey, and 1/4 cup heavy cream. Bring to a gentle boil, stirring constantly.
Step 7: Remove from heat and stir in the blanched sliced almonds. Let it cool slightly.
Step 8: Once the dough has doubled, gently punch it down. Roll it out into a 10-inch circle and carefully transfer it to a greased 10-inch springform pan.
Step 9: Spread the cooled almond topping evenly over the dough.
Step 10: Cover the pan loosely and let the cake rise again in a warm place for another 30-45 minutes, or until puffy.
Step 11: Preheat your oven to 350°F (175°C).
Step 12: Bake for 30-35 minutes, or until the cake is golden brown and the almond topping is caramelized and bubbly. Loosely tent with foil if browning too quickly.
Step 13: Remove from the oven and let cool completely in the pan on a wire rack before carefully removing from the springform pan.
Step 14: For the filling, whisk together egg yolks, 1/2 cup sugar, cornstarch, and a pinch of salt in a medium saucepan until smooth.
Step 15: Gradually whisk in 2 cups milk. Add scraped vanilla seeds and pod (if using).
Step 16: Cook over medium heat, whisking constantly, until the mixture thickens significantly and boils gently. Continue whisking for 1 minute.
Step 17: Remove from heat. Remove vanilla pod. Stir in 2 tablespoons butter and vanilla extract (if not using a bean).
Step 18: Pour custard into a clean bowl, cover surface directly with plastic wrap, and chill for 2-3 hours until completely cold and firm.
Step 19: In a separate bowl, whip 1 cup heavy cream until stiff peaks form.
Step 20: Once custard is chilled, gently fold the whipped cream into the cold custard until fully combined and light.
Step 21: Carefully slice the cooled cake horizontally into two layers using a long serrated knife.
Step 22: Spread the vanilla cream filling generously over the bottom cake layer.
Step 23: Carefully place the top cake layer (with the almond topping) over the cream filling.
Step 24: Chill the assembled cake for at least 1 hour before serving to allow the filling to set and flavors to meld. Slice with a sharp, serrated knife.