Preheat the oven to 375 degrees and prepare a 12 count muffin pan with cupcake/muffin liners. Set aside.

In a large bowl, whisk together the flour, baking soda and salt. Set aside.

Melt the chopped baking chocolate and butter in the microwave or stove top until melted and stir until smooth. Allow the mixture to cool for 5 minutes.

Use an electric mixer on medium low speed and add the sugar, cocoa, eggs, vanilla extract and sour cream until well incorporated.

Reduce speed to low and combine the flour mixture with the chocolate mixture until fully mixed.

Gently fold in 1 cup of the dark chocolate chips, reserving ½ cup for after baking.

Bake for 20 minutes or until a toothpick or knife inserted in a middle muffin comes out mostly clean.

Remove the muffins from the oven and top with the remaining chocolate chips, pressing lightly into the tops of the muffins.

Allow to cool before serving.