Preheat the oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper liners.

Whisk the dry ingredients: In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.

Combine the wet ingredients: In a separate bowl, whisk together the melted butter, vegetable oil, sugar, and vanilla extract until well combined. Add the milk and eggs, one at a time, and whisk until just incorporated.

Gradually add the wet ingredients to the dry ingredients: Pour the wet ingredients into the dry ingredients and whisk until just combined. Be careful not to overmix.

Incorporate the hot coffee: Slowly add the hot coffee (or hot water) and mix until a smooth batter forms.

Fill the cupcake liners: Divide the batter evenly among the prepared cupcake liners, filling them about ¾ full.

Bake the cupcakes: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Cool the cupcakes: Let the cupcakes cool in the pan for 10 minutes before transferring them to a wire rack to cool completely.

Make the whipped cream filling: While the cupcakes cool, whip the heavy whipping cream, powdered sugar, and vanilla extract in a chilled bowl until stiff peaks form.

Assemble the cupcakes: Once the cupcakes are cool, use a cupcake corer or a sharp knife to remove a small center core from each cupcake. Fill the hollow center with whipped cream. You can also pipe the whipped cream onto the top of the cupcakes using a piping bag fitted with a star tip.