In a medium sized bowl, whisk together the sugar, cornstarch, and salt. Add the egg yolks and whisk together until the mixture is pale and smooth, about 1 minute. At first the mixture will seem too dry but keep whisking and it will loosen and then become smooth. Whisk in the milk, a splash at a time for the first 1/2 cup, until all of the milk has been fully incorporated.

Pour the mixture into a small saucepan and cook over medium-low heat while whisking constantly. Once it begins to gently boil, continue to cook for an additional 1 minute to cook out the starch. Remove from the heat and whisk in the vanilla extract.

Push the pastry cream through a fine-mesh strainer into a clean bowl using a spatula. Cover with plastic wrap and place it directly on the surface of the pastry cream. Chill in the fridge while preparing the cake.

Preheat your oven to 350F and spread the almonds on a large baking sheet. Toast for 10 minutes or until lightly toasted. Set aside to cool.

In the bowl of a stand mixer or a large bowl add the instant yeast, sugar, flour and salt. Whisk together to combine. Whisk together the melted and cooled butter, milk, eggs and lemon zest in the saucepan that the butter was melted in. Pour the wet ingredients on top of the dry ingredients and fit the stand mixer with a paddle attachment or use a hand mixer.

Mix on low-medium speed for 2 to 3 minutes until completely incorporated. Scrape down the sides of the bowl, cover tightly and allow to rise for 60 minutes. Note that the mixture will not double, however, it will puff up and look bubbly.

Butter a 9" springform pan then line the bottom with a round of parchment paper. Cut a second round of parchment paper for the topping and set aside. Butter the parchment paper as well. Once the batter has finished its first rise, stir it with a spatula to deflate it, then empty it into the prepared springform pan and gently spread evenly so it fills the bottom of the pan. Cover tightly again and allow to rise for 30 minutes. Note that is will not double at this point either, but will puff up slightly again and look bubbly.

While the cake is rising for the second time, make the topping. In a medium saucepan, combine and heat the butter, sugar, honey, whipping cream and salt over medium heat. Bring to a simmer and allow the mixture to boil for 3-5 minutes while stirring frequently. The mixture will turn a shade darker. If you have a candy thermometer, the mixture is done when it reaches 240F. Stir in the lightly toasted almonds, then empty the mixture out onto the second circle of parchment paper. Use a spatula to spread the mixture evenly, leaving a 1/2 inch gap around the edge of the parchment circle. Set aside to cool.

Preheat your oven to 350F. Bake the cake on the center rack for 12 minutes then remove from the oven, peel the topping off the parchment circle and gently place the topping onto the cake. Bake for another 15-17 minutes or until a toothpick inserted into the center comes out clean. Move the cake to the top rack and broil on high for 1-2 minutes to darken the almond topping (optional). Remove and place the cake and springform pan on a wire rack to cool for 30 minutes.

After 30 minutes, run a sharp knife around the outside of the cake and remove the springform pan sides. Allow the cake to cool completely.

In the bowl of a stand mixer with the whisk attachment or in a large bowl with a hand beater, beat the whipping cream until stiff peaks form.

Remove the pastry cream from the fridge and use a whisk to stir it up until it is smooth and creamy again. Add half of the whipped cream and gently combine with a spatula then fold in the rest of the whipped cream.

Place the cake on a cutting board and cut it into two layers using a long serrated knife or bread knife. Move the top layer to another cutting board or onto a wire cooling rack. Place the bottom layer onto a cake plate or serving platter. Place the outer ring of the spring form pan around the bottom layer, then spread the filling evenly over the bottom layer of the cake, right to the edges of the spring form pan.

Move the top layer to a cutting board if it was on a cooling rack and use a long serrated knife or bread knife to cut the top layer into 8 or 12 slices. Place each slice inside the spring form pan ring on top of the filling. Gently press down on each piece to adhere it to the filling below.

Cover and chill the entire cake as is for a few hours in the fridge. This helps set the filling and makes the cake easier to slice. When ready to serve, run a sharp knife around the inside edge of the spring form pan, then remove it from the cake. Cut into slices all the way through the filling and the bottom layer and serve.