1. Preheat oven to 350 degrees F. Grease and line the bottom of a nine inch springform pan with parchment paper.
2. Whisk flour, baking powder and salt.
3. In the bowl of a stand mixer fitted with the paddle attachment, beat the peanut butter and sugar on medium speed for about 2 minutes.
4. Decrease speed to low, and add eggs, 1 at a time. Mix in vanilla extract.
5. Add the flour mixture and mix until just combined.
6. Pour batter into the prepared baking pan and bake for 30-35 minutes, or until a wooden skewer inserted in the center comes out clean.
7. Remove cake from oven, and let cool completely in the pan.
8. Using a wooden skewer or toothpick, poke holes all over the cooled cake. The more holes, the better! Place the cake pan on a larger deep platter to avoid any messes!
9. Combine the whole milk, sweetened condensed milk, and half and half in a large glass measuring cup. Gently pour the milk mixture over the top of the cake. It may look like a lot of liquid, but the cake will soak it all up. Let sit for 30 minutes.
10. Add the heavy cream to a mixing bowl and beat with the whisk attachment until stiff peaks form. Spread over the cake
11. Refrigerate cake for at least 4 hours or overnight before serving.