Heat oven to 350°F. Line cupcake pans with wrappers.
Stir together the ingredients of the jar. Add eggs, milk, oil and vanilla; beat on medium speed of mixer 2 minutes. Stir in hot coffee (batter will be thin). Pour batter into prepared pans.
Bake 20-25 minutes or until wooden pick inserted in center comes out clean.
Notes
The jar of cake mix referred to in the recipe is our homemade Chocolate Cake Mix in a Jar.To prepare the jar, layer the ingredients in order in a 1 quart mason jar and attach the baking instructions (printable version here)