Chocolate Cupcakes with Peanut Butter Frosting

This is probably the most moist, picture perfect cake I've made.  It was a different kind of recipe in that it used oil instead of the butter like I normally use.  They "domed" ideally too.  Found the cake recipe off tastykitchen.com and the frosting recipe off food.com

Chocolate Cupcakes with Peanut Butter Frosting

cake:

• 2 cups Flour
• 2-½ cups Sugar
• ¾ cups Unsweetened Cocoa Powder
• 2 teaspoons Baking Soda
• 1 teaspoon Salt
• 1 cup Vegetable Oil
• 1 cup Sour Cream
• 1 teaspoon Instant Espresso Or Instant Coffee Granules
• 1-½ cup Water
• 1 teaspoon Vanilla Extract
• 2 Tablespoons White Vineger
• 2 whole Large Eggs, At Room Temperature

1.Mix the flour, sugar, cocoa powder, baking soda, and salt in a large bowl. Whisk to combine them well.
2. Add the oil and sour cream and whisk to blend.
3. Mix the ground espresso into the water then gradually beat into the batter mixture.
4. Blend in the vinegar and vanilla.
5. Whisk in the eggs and beat until well blended. Scrape down the sides of the bowl and be sure the batter is well mixed.
6. Divide among the 3 prepared cake pans.
7. Bake for 18 minutes, or until a cake tester or wooden toothpick inserted in the center comes out almost clean.  Let cool completely before frosting.

frosting:

• 1 cup butter (softened to room temp)
• 1 cup creamy peanut butter
• 4 cups powdered sugar
• 1/4 cup milk
• 2 teaspoons vanilla

1. Cream butter and peanut butter together.
2. Add half the powdered sugar and blend.
3. Blend in milk and vanilla.
4. Add remaining powdered sugar.
5. Stir until smooth and well blended. 
   Fill in decorator gun and pipe on top of cupcakes.