• Preheat the oven to 375 degrees and line a 9x9 baking dish with parchment paper (or grease it well). Set aside.

Crumb Topping:

• In a small bowl, whisk together flour and sugar. Drizzle in the melted butter and mix until it resembles coarse sand. Use your hands to break into smaller pieces. Set aside.

Lemon Cake:

• In the bowl of a standing mixer (or in a large bowl with a hand mixer or rubber spatula), add granulated sugar and lemon zest together. Rub the mixture together to release the natural oils in the lemon zest, which makes the cake so much more flavorful.
• Add in the remaining dry ingredients: all purpose flour, baking powder, and salt. Whisk until combined. Make a small well in the center of the dry ingredients (this allows the liquid to be dispersed evenly and prevent over mixing).
• Whisk together melted butter, buttermilk, vanilla extract, almond extract, and the egg. Pour into the center of the dry ingredients, then mix until just combined.
• Lastly, add in the greek yogurt, and mix until just combined.

Assembly:

• Pour the lemon batter into the prepared cake pan, spreading into an even layer.
• Depending upon how much lemon curd you want, dollop anywhere from 1/4-1/3 cup of lemon curd on top of the cake. Using a toothpick or a knife, gently swirl the curd into the cake.
• Lastly, sprinkle the crumb topping on top.
• Bake for about 25-30 minutes, or until a cake tester comes out clean and the crumb streusel topping is lightly golden on top.

Icing:

• While the lemon crumb cake is cooling, make the icing. Whisk together 1 Tbsp of lemon juice, lemon zest, and powdered sugar together. If the icing is too thick, add in the remaining Tbsp of lemon juice. Drizzle on top of the cake.
• This lemon crumb cake can be served warm, at room temperature, or cold.