Preheat oven to 350°F. Prepare 2 cupcake pans (24 total cupcakes) with cupcake liners. In a large mixing bowl, add the flour, baking soda, baking powder, and salt. Whisk together to combine. Set aside.

In another large bowl, add eggs, sugar, sour cream, vegetable oil, and vanilla. Whisk together until smooth and well combined.

In a small mixing bowl or 2-cup liquid measuring cup, add the hot coffee and cocoa powder. Whisk together until well-combined and smooth. Allow to sit for 2 minutes, then add the cocoa mixture into the mixing bowl with the wet ingredients (eggs, sour cream, etc.), then mix until smooth.

Add the wet ingredients into the bowl with the dry ingredients, and mix until smooth. Pour the cake batter into the prepared cupcake pans, filling 2/3 full, and bake for 20 minutes or until an inserted toothpick comes out clean. Allow to cool completely before frosting.

Add 2 cups of confectioners sugar and lavender to a food processor. Process until no large pieces of lavender are apparent – about 3-4 minutes. Using a fine mesh sieve, sift the lavender sugar to remove any leftover large pieces of lavender and discard them. Set the sugar aside.

Add butter to a stand mixer fitted with the whisk attachment. Beat on high until butter is doubled in volume, and looks light and fluffy.

Turn the stand mixer to low and slowly add the lavender confectioners sugar and the other 5 cups of confectioners sugar. Beat until completely incorporated, then add in the blackberry jam and salt. Beat until well-combined and fully incorporated.

Pipe onto cooled cupcakes.