In the bowl of an electric mixer fitted with a paddle attachment, cream the butter and sugars on high until light and fluffy (2-5 minutes).
Lower the speed and add the eggs. Mix well. Add the vanilla. Add yogurt, buttermilk, and hot chocolate. Mix well.
Add baking soda and salt. Mix well.
Finally, add in the flour and mix only until blended. Check the batter with a spatula to be sure it's completely blended.
Fill greased cake pans** or cupcake pans ⅔ full.
Bake in the middle of the oven for 15 to 25 minutes, until a toothpick comes out clean. Cool for 10 minutes; remove from the pans. Cool completely before frosting.
Meanwhile, beat peanut butter and butter on high until it’s smooth. Add powdered sugar, vanilla, and salt and mix until creamy, scraping down the bowl with a rubber spatula as you work.
Add 3 tablespoons of the cream and beat on high speed until the mixture is light and smooth. Add up to 3 more tablespoons until you reach your desired consistency.
Frost the cakes and cupcakes. If you're doing a double layer cake, I like to put strips of wax paper around the cake to keep the tray clean. Also, you may need to use a serrated knife to level the bottom layer of the cake.
Slather a thin layer of frosting between the two cakes.
Add the top layer and frost the entire outside of the cake. To decorate, I taped waxed paper over a heart-shaped cookie cutter.
I then tapped cocoa powder around it to create a heart border on the cake.
Then I added chopped salted peanuts.
I frosted the cupcakes and garnished them with peanuts as well.
Notes
Makes an 8” double layer cake, or 1 small 2 cup heart cake and 8 cupcakes or 15 cupcakes. *If you don’t have it on hand or feel like making it, then add 1 cup buttermilk (here’s how to make buttermilk at home) and 3 ounces melted very dark chocolate (I used 72% cacao but unsweetened would be great too). **Peanut butter brands vary a lot, so having some wiggle rooms is a good thing. I use homemade peanut butter which is great because it doesn’t have sugar in it, but to get the fluffiest, smoothest, you actually want to use something commercial, like skippy. I like the little bit of texture that natural peanut butter adds, but just keep in mind the peanut butter will affect the texture a lot.Adapted from Ina Garten