Preheat oven to 350°F. Grease a 12-cup muffin pan.

Place the dry ingredients in a large bowl. Whisk to combine.

Place the wet ingredients in a medium bowl. Use a mixer to mix them until well combined.

Add the wet ingredient mixture to the dry ingredient mixture. Use a mixer to mix them until the batter is well combined.

Pour or spoon the batter into the muffin cups, dividing evenly.

Bake for 15 to 20 minutes. The cupcakes are done when a toothpick inserted in the center comes out clean.

Remove the cupcakes from the pan and place them on a wire rack to cool completely.

Place coconut oil in a small microwave-safe bowl. Microwave until the oil is melted, about 30 seconds.

Add the peanut butter and stir to combine. Microwave the mixture in 10-second increments if needed to give it a pourable consistency so it runs off a spoon.

Drizzle the icing over each cupcake. Allow the icing to cool to room temperature.