Melt ½ cup of unsalted butter and 6 ounces of semisweet chocolate in a microwave-safe bowl, heating in 30-second intervals until smooth. Allow to cool slightly.

Stir in 1 cup of granulated sugar, then add 2 large eggs one at a time, mixing thoroughly after each. Add 1 teaspoon of vanilla extract.

In another bowl, whisk together ½ cup of all-purpose flour and ¼ teaspoon of salt. Fold the flour mixture into the chocolate mixture until just combined.

Prepare a mini muffin pan by lining it with cupcake liners. Fill each cup one-third full with brownie batter.

Preheat your oven to 350°F (175°C). Bake the brownie bases for about 8 minutes, then allow to cool slightly.

In a mixing bowl, beat 8 ounces of softened cream cheese until smooth. Gradually add ½ cup of granulated sugar and 1 teaspoon of vanilla extract, mixing well.

Incorporate 1 large egg and ½ cup of sour cream, blending until velvety and free of lumps.

Spoon the cheesecake mixture over the cooled brownie bases, filling nearly to the top.

Lower the oven temperature to 325°F (163°C) and bake for 15-18 minutes, or until the edges are set and the centers have a gentle wobble.

Let the cheesecakes cool in the pan for about 30 minutes, then transfer to the refrigerator to chill for at least 2 hours.