PREHEAT THE OVEN AND PREPARE THE PAN

1. Preheat oven to 325°F.
2. Grease a 9×9-inch light-colored metal baking pan and line with parchment paper.

PREPARE THE CAKE BATTER

1. In a large bowl or the bowl of a stand mixer, combine the granulated sugar and lemon zest. Rub together with your fingertips until fragrant.
2. Add the gluten-free 1:1 flour, almond flour, baking powder, baking soda, and salt. Whisk to combine.
3. Add the softened, cubed butter. Using a hand mixer or stand mixer fitted with the paddle attachment, mix until the butter is fully incorporated and the mixture resembles coarse crumbs.
4. In a separate bowl, whisk together the eggs, milk, sour cream, oil, lemon juice, vanilla extract, and almond extract until smooth.
5. Pour the wet ingredients into the dry ingredients and mix on low speed until a smooth batter forms.
6. Stir in the poppy seeds until evenly distributed.

BAKE THE CAKE

1. Spread the batter evenly into the prepared pan.
2. Bake for 35–45 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
3. Cool completely in the pan on a wire rack.

MAKE THE FROSTING

1. In a large bowl, beat the butter, cream cheese, and salt until smooth and creamy.
2. Gradually add the powdered sugar and mix until fully incorporated, scraping down the bowl as needed.
3. Add the vanilla extract, almond extract, and 1 tablespoon of cream or milk. Beat until light and fluffy. Add more cream or milk as needed to reach a spreadable consistency.

ASSEMBLE AND SERVE

1. Spread the frosting evenly over the cooled cake.
2. Spoon the lemon curd over the top.
3. Use an offset spatula or knife to gently swirl the lemon curd into the frosting.
4. Slice into squares and serve.

Store the frosted cake covered or in an airtight container in the refrigerator for up to 4 days. For the best texture and flavor, let slices sit at room temperature for 15–20 minutes before serving.