For the Cake:

1. Preheat your oven to 350°F (175°C). Grease and sugar a bundt pan.
2. In a large mixing bowl, cream the butter and sugar until light and fluffy.
3. Mix in the peanut butter until smooth.
4. Add eggs, one at a time, mixing after each addition.
5. In a separate bowl, whisk together flour, baking powder, and salt.
6. Gradually alternate adding the dry ingredients and buttermilk into the butter mixture. Start and end with the dry ingredients.
7. Stir in the vanilla extract.
8. Pour the batter into the prepared bundt pan and smooth the top.
9. Bake for 75–85 minutes or until a toothpick comes out clean.
10. Cool the cake in the pan for 30 minutes, then invert onto a wire rack to cool completely.

For the Frosting:

1. Beat together the peanut butter, vanilla, and corn syrup until smooth.
2. Gradually add powdered sugar, alternating with heavy cream, until the frosting is thick but spreadable.
3. Spread the frosting over the cooled cake and let it drizzle down the sides.