Preheat the oven to 180C/350F and get out a 12 hole donut pan (mine are about 21/2 inches in diameter - the number of donuts will change depending on the pan).
Place all the ingredients for the donuts, in order, into a large mixing bowl and stir together until combined and lump free. Pipe or spoon the mixture into the donut pan, filling each one no more than halfway full.
Stir together all the ingredients for the streusel into a clumpy mass, and scatter evenly over all the donuts.
Bake for 10-12 minutes, or until they spring back when touched.
Cool on a wire rack and serve - these are great warm.
Recipe by The Sugar Hit at http://www.thesugarhit.com/2016/04/coffee-cake-donuts.html