Preheat oven to 350 to 375 degrees. This depends on your oven. My oven cooks hot so I heated my oven to 350.
Line a 12-inch _or larger) pizza pan or tart pan with parchment paper. With this dough, you must use parchment paper. Anything else it will stick to.
In a microwave-safe bowl combine the first six ingredients. All EXCEPT for the eggs, sweetener, vanilla, and sour cream.
Heat in microwave for 1 1/2 to 2 min stirring every 30 seconds.
Mix very well till a dough forms.
Divide the dough. On a piece of parchment paper, roll or press the dough into a 12-inch round (or size of your pan). You will want to make 2 to 3 rounds. I made 2.
Carefully transfer one round onto the prepared pan.
Spread half the streusel over dough to within 1 inch of the edge.
Set another round on top of the filling. Spread remaining streusel over the dough. Press edges.
If you have any extra dough you can roll it between your hands until it makes a long piece that will fit around the edge. then press to the edge of your cake.
Tent cake with foil. Bake coffee cake for about 20 min. You can remove foil and cook for a few mins at the end to get a golden color on top.