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Preheat oven to 350. Place cupcake liners in a 12-cup muffin tin, or spay a 9-inch cake pan.
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In a small bowl, sift together flour, baking powder, baking soda, and salt.
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In a second bowl, mix melted butter and oil together. Add in sugars and stir (mix will be gritty).
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Stir in eggs, milk, vanilla, and yogurt and mix until blended.
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Slowly, incorporate the dry ingredients into the wet ingredients, stirring gently.
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Once the mix is just combined, transfer 1 cup of the batter into a new bowl.
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Whisk in cocoa powder, coffee, and espresso powder.
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Pour vanilla batter into muffin cups, about 1/4 way full.
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Now, alternately spoon in chocolate and vanilla batter until each cup is 3/4 of the way full.
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Take a tooth pick or cake tester to gently swirl the batters together.
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Bake for 20-22 minutes or until a cake tester comes out clean.