Mix dry ingredients in a large bowl. Whisk egg, sour cream, and oil in a separate bowl. Add egg mixture to the dry ingredients and gently mix until batter is smooth.
Place 2 six-hole silicone donut pans on a baking tray. Lightly brush with oil as added insurance that donuts will not stick to the mold. Pour batter into each donut hole, about ¾ full. Bake for 28 to 30 minutes or until donut top springs back slightly when touched. Remove from oven and allow to cool for 5 minutes before inverting and unmolding on a rack. Cool completely.
To make the chocolate glaze, heat cream in a small sauce pot. When simmering, whisk in cocoa powder until smooth. Pour hot cream over your bowl of chocolate chips. Cover for 5 minutes to soften the chocolate then slowly mix until you get a smooth texture. Add butter and mix to get a shiny glaze. Cool to room temperature.
Holding the donut around its bottom part, dip the domed surface in the chocolate glaze, about halfway around the donut. Lift and lightly shake to remove excess glaze. Carefully set on the rack. Do the same with the rest of the donuts. Top donuts with candy sprinkles.