Mix oat flour, cocoa powder, Splenda magic baker, baking powder, salt, cinnamon, and nutmeg.
Add egg, vanilla Greek yogurt, and vanilla extract. Mix well.
In a shallow bowl, mix Splenda magic baker and cinnamon for the dip.
Oil 4 doughnut forms on the doughnut pan.
Place batter in a ziplock bag, cut a corner off, and pipe even amounts of mixture into the 4 prepared doughnut forms. Smooth tops.
Bake at 350 degrees for 15 minutes. Let rest for 10 minutes.
Remove from pan and dip into cinnamon sugar before serving.
