Preheat the oven to 350F and spray the either a christmas tree-shaped or 8x8 baking dish with non-stick spray.
Pulse all the ingredients for the struesel in a food processor until it’s a crumbly texture. Keep in the fridge until it’s time to use it.
Using an electric mixer fitted with a beater attachment, cream the butter and sugar. Add in the eggs, greek yogurt, and vanilla extract. Beat on a low speed until everything is just combined.
Add in the dry ingredients (flour, baking powder, baking soda) and mix on a slow speed. The batter will be thick and a little lumpy when mixed together.
Scoop half of the batter into your baking dish. Sprinkle half the struesel across it evenly. Scoop and dollop the rest of the batter on top of the stuesel layer so that it’s fully covered. Sprinkle the rest of the struesel on top.
Bake the coffee cake until a toothpick comes out clean when inserted in the center, about 45-50 minutes. Set the coffee cake on a wire rack to cool in the pan while you make the glaze.
Whisk together the powdered milk, maple syrup and milk until smooth. Add more milk as needed to thin the glaze. Drizzle the glaze over the coffee cake and serve warm.