Cream butter and sugar together and add eggs one at a time. Then add in all the milk until mixture is smooth.
Beat in baking powder and flour. Batter should be a thick sticky mixture.
Preheat oven to 350 °F. and grease a 8 or 9-inch springform pan. Pour cake batter into greased pan and set aside.
In a medium sauce pan, melt butter, sugar, and honey to make the cake topping. Fold in all the slivered almonds into hot melted sugar butter mixture. Pour topping over unbaked cake batter evenly.
Bake cake for about 40 minutes or until topping is lightly brown and toothpick comes out clean from interior part of cake. Tip: place some aluminum foil on bottom of oven to help with possible spillage of cake topping when baking.
Pastry Cream
Heat milk and vanilla together. Heat milk to make it warm to the touch but not scolding or boiling.
In a separate bowl whisk together egg yolks, white sugar, and cornstarch. Slowly add warm milk to egg mixture constantly whisking and slowly warming the eggs without cooking and making scrambled eggs.
Heat entire mixture in a saucepan over medium heat. Continue whisking constantly. Heat until cream thickens.
Remove from heat, pour cream into shallow bowl and bring it to room temperature. Then store in the refrigerator for a few hours.
Cut the cake in half and spread the pastry cream then top with the rest of the cake.