1/2 pound butter at room temperature.
2 1/2 cups sugar, divided
4 extra-large eggs at room temperature
1/3 cup grated lemon zest (6-8 large lemons)
3 cups gluten free flour (I like Bob's)
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1 teaspoon kosher salt
3/4 cup freshly squeezed lemon juice, divided
1 teaspoon vanilla
3/4 cup buttermilk at room temperature
For the glaze you will need:
2 cups powdered sugar
3 1/2 tablespoons freshly squeezed lemon juice
Preheat the oven to 350 degrees, grease your pan
Cream the butter and two cups sugar in the bowl of an electric mixer fitted with the paddle attachment, for about five minutes, or until light and fluffy. With the mixer on medium speed, add the eggs, one at a time, then add the lemon zest.
Sift together the flour, baking powder, soda and salt in a bowl. In another bowl combine 1/4 cup lemon juice, the buttermilk and vanilla. Add the flour and buttermilk mixtures alternately to the batter, begin and end with the flour. Pour batter into the pan, smooth the tops and bake for 45 minutes to an hour, until a cake tester comes out clean.
Combine 1/2 cup sugar with 1/2 cup lemon juice in a small saucepan and cook over low until the sugar dissolves. When the cake is done, let it cook for 10 minutes, then invert the cake onto a rack, set over a tray, and poke holes in the cake with a long wooden toothpick. Spoon the lemon syrup over the cake and allow to cool completely.
For the glaze, combine the powdered sugar and lemon juice in a bowl and mix with a wire whisk until smooth. Pour over the top of the cake and allow the glaze to drizzle down the sides.