In a large bowl, cream butter and sugar either with a hand mixer. Start on low and then continue to cream on medium speed for 2-3 minutes until it is a pale yellow color and creamy. If it's gritty it's undercreamed and if it's greasy it is over creamed.
Sift flour with baking powder into the bowl with the creamed butter and sugar. Use your hands to working it all into fine crumbs.
Take 3/4 cup of crumble mixture and reserve for the struesel.
Add eggs, milk, and vanilla extract to the rest of the mixture and mix into a thick batter.
Grease your baking pan (either 8x8 or 9x13) and add batter to the pan in an even layer.
Add melted butter, brown sugar, cinnamon, and nutmeg to the bowl with the reserved crumble and mix until well combined and crumbly.
Sprinkle the struesel topping evenly over the batter in the baking pan.
Bake for 30-35 minutes for a 9X13 pan or 45-50 minutes for an 8X8 pan, or until a toothpick or cake tester pulls clean from the center.
Serve warm and enjoy!
Video
Notes
Pan SizeYou can make this recipe in a 9X13 pan or an 8X8 for larger thicker slices. We prefer the 8X8 for ultimate fluffy pieces. For 9X13, bake for 30-35 minutes, and for 8X8, bake for 45-50 minutes. Always check for doneness with a cake tester, toothpick, or knife by inserting it into the center of the pan and removing slowly. If it comes clean, your cake is fully cooked. If not, bake for another minute or two before checking again. Make-AheadPrep everything and cover with plastic wrap and store in the fridge overnight. Remove from fridge and bake when ready. StorageFridge: Cover in plastic wrap and store in the fridge for up to a week or on the counter in an airtight container for up to 3 days.Freezer: Wrap in foil and store in a plastic bag in the freezer for up to 3 months. Remove and let defrost at room temperature or in the fridge.SubstitutionsFlour: You can use gluten-free flour, but be sure that it has xantham gum.Milk: Use 1% - Whole. Butter: Use unsalted butter and just add 1/4 teaspoon of salt to your flour and baking powder.Vanilla Extract: Use almond extract to add a delightful nutty flavor!