Preheat the oven to 350°F. Lightly grease and line a 9x9 inch square baking pan or springform pan with parchment paper.

First make the lemon sugar. Put the sugar and lemon zest into a food processor and process until the zest is completely incorporated into the sugar and it's pale yellow and fragrant. If you don't have a processor, use a small bowl to finely grate the lemon zest into the sugar, using your fingers to help release the oils from the zest into the sugar.

Then, prepare the crumb topping. In a medium bowl, sift together all of the dry ingredients for the crumble topping. Then, using a fork or your fingers (I prefer fingers) combine everything with the cold butter until the mixture is crumbly. Alternatively, you can use a food processor and pulse the dry ingredients to combine and then add the butter, pulsing until you achieve the same crumbly texture. Refrigerate until ready to use. NOTE: It's important to use cold butter to get the desired consistency of the crumb topping.

Now make the cake. In a large bowl, cream the sugar and butter together until pale and fluffy, scraping down the bowl as necessary. You can do this in a stand mixer or with a fork.

Beat in the eggs, one at a time, beating well. Blend in the vanilla. Add the buttermilk. It will change the texture of the mixture, but don’t worry. This is normal.

In a separate bowl, whisk together the flour, baking powder and salt.

Then add the flour mixture to the large bowl with the wet ingredients and blend until almost incorporated. Stir until everything is mixed, but don't over do it. Gently fold in the strawberries.

Spoon the (thick) batter into the prepared square pan and spread it out evenly. Sprinkle crumb topping on the cake. Bake for 50-55 minutes in the preheated oven, or until golden and a toothpick inserted in the center comes out clean.  If the cake looks too brown, cover it toward the end of baking with aluminum foil. Serve this delicious cake with coffee, tea or macerated strawberries and a scoop of vanilla ice cream.