Preheat oven to 350 degrees (F). Spray your donut mold with non-stick spray and set aside.
In a medium-sized bowl whisk together the flour, light brown sugar, salt, and baking powder.
In a separate bowl mix the sour cream, melted butter, egg, and instant coffee. Make sure the melted butter has cooled or it will curdle the sour cream and cook the egg. Gently fold the wet ingredients into the dry ingredients. The dough will be much thicker than you think it will be, so don’t be alarmed.
Spoon the batter into your molds and fill them up to the top. If you’re using a silicone mold, place it on a cookie sheet before you put them in the oven, this will make it easier to get them in and out of the oven.
Place your donuts in the pre-heated oven. The donuts usually take about 15-17 minutes to bake, but I started checking them around 10 minutes to see if the pan needs to be turned. You’ll know they are finished when you lightly press on a donut and it springs back.
Remove from oven and allow to cool in the pan for 10 minutes and then remove from pan and allow to cool completely before glazing.