1-First, preheat the oven to 350°F (175°C) and grease a 9-inch round springform pan; this sets the stage for even baking.

2-In a bowl, whisk together the all-purpose flour, almond meal, baking powder, and salt; mixing dry ingredients ensures even distribution.

3-In a separate large bowl, cream the unsalted butter with granulated sugar until light and fluffy; this step is crucial for a tender crumb.

4-Beat in the eggs one at a time, ensuring each is fully incorporated; for vegan adaptation, use flax eggs.

5-Add lemon juice and lemon zest to the wet mixture and blend well to infuse the cake with lemon flavor.

6-Gradually fold the dry ingredients into the wet mixture, mixing gently to maintain airiness and prevent overmixing.

7-Pour the batter into the prepared cake pan, smoothing the top for even baking.

8-Top with the streusel mixture by combining 2 cups brown sugar, 2 1/4 cups all-purpose flour, zest of half a lemon, 1 cup melted unsalted butter, a pinch of salt, and 1 1/2 cups slivered almonds to create clumps.

9-Bake for 50 to 60 minutes, or until a toothpick inserted in the center comes out clean or with moist crumbs; this longer bake time ensures the streusel sets perfectly.

10-Let the cake cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

11-Once cooled, prepare the glaze by mixing 2 cups powdered sugar, 2 to 3 tablespoons lemon juice, and 1 teaspoon vanilla extract, then drizzle it on top for a shiny finish.