Preheat the oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.

Combine oil, granulated sugar, buttermilk, egg, and vanilla extract in a large bowl. Whisk until the mixture is smooth and well-blended.

Mix sour cream, flour, cocoa powder, baking soda, instant coffee, and salt in another bowl. Stir these dry ingredients together until fully incorporated.

Fold the dry ingredients into the wet ingredients gradually, ensuring everything is just combined. Gently mix in the chocolate chips.

Beat the cream cheese, granulated sugar, sour cream, egg, and vanilla extract in a separate bowl until smooth and creamy.

Fill the muffin tins halfway with chocolate batter, then dollop a spoonful of the cream cheese mixture on top. Cover with the remaining chocolate batter.

Bake in the preheated oven for about 25 minutes, or until a toothpick inserted into the center comes out clean.

Cool the muffins in the pan for a few minutes before transferring them to a wire rack. Allow them to cool completely before serving.