• Preheat your oven to 350°F. Grease an 8-inch square baking pan, then line it with crisscrossed sheets of unbleached parchment paper, overhanging both sides of the pan. Set the pan aside.

Make the batter.

• In a large bowl, place the flour, xanthan gum, baking powder, baking soda, salt and sugar, and whisk to combine well.
• Create a well in the center of the dry ingredients and add the butter, yogurt and eggs, mixing to combine after each addition. The batter will be thick.
• Add 1 cup of the chopped strawberries and mix gently until the strawberries are evenly distributed throughout the dough, taking care not to crush the strawberries.
• Scrape the batter into the prepared pan and spread into an even layer with a wet spatula. Scatter the remaining 1/4 cup chopped strawberries over the top of the batter, pressing them gently into the batter.

Bake the cake.

• Place the pan in the center of the preheated oven and bake until a toothpick inserted in the center comes out clean and the top is very lightly golden brown (about 25 minutes).
• Remove from the oven and allow to cool in the pan for 10 minutes before lifting out by the overhung parchment paper and placing on a wire rack to cool (peeling off the parchment from the bottom of the cake if possible).
• Allow the cake to cool completely before slicing into 16 squares and serving.

Storage.

• The cake freezes really well. Just wrap the pieces tightly in freezer-safe wrap and freeze. Defrost at room temperature and then refresh in a 250°F toaster oven for a minute or two before serving.