Preheat oven to 350 degrees. Coat or grease a 9x13 baking pan.
In the bowl of a stand mixer fitted with a paddle attachment or large mixing bowl, whip butter until light and fluffy. Add both sugars and continue to blend well.
Add salt, baking powder and vanilla, mixing well. Add yogurt and continue to blend.
Add eggs, one at a time, mixing completely between additions.
Alternate adding milk and flour until fully incorporated. Set aside.
In a medium bowl, mix together all ingredients for filling. Mix will be dry and crumbly.
Pour 1/2 of cake batter into prepared 9x13 baking dish, spread evenly. Top with filling. Spoon remaining batter on top of filling. Gently spread out over filling.
Clean out and dry large mixing bowl for your stand mixer (or mix by hand). Combine all ingredients for cinnamon streusel topping, blend well until all dry ingredients have been moistened. Mixture will be dry and crumbly.
Evenly sprinkle over cake batter, patting down lightly.
Bake for 60 minutes, or until cake passes toothpick test. Allow to sit for 20 minutes before serving.
If you've tried this recipe, come back and let us know how it was!