Do-si-do Cupcakes

Ingredients

• 1/2 tsp vanilla extract
• 1/4 teaspoon salt
• 1 1/2 teaspoon baking powder
• 1 teaspoon vanilla
• 1/2 cup buttermilk
• 1/2 cup creamy peanut butter
• 1 large egg (room temperature)
• 3 tablespoons heavy cream
• 1 cup (140g) all-purpose flour
• 6 tablespoons (3oz) unsalted butter (room temperature)
• 3/4 cup (190g) smooth peanut butter
• 1 cup (200g) packed brown sugar
• 3 tablespoons (1.5oz) butter (room temperature)
• 1/3 cup (66g) packed brown sugar*
• 1/3 cup (40g) powdered sugar