Preheat the oven to 350°F and lightly grease a 9 by 5-inch loaf pan with nonstick spray.
Whisk butter, oil, brown sugar, granulated sugar, and lemon zest in a bowl until light and fluffy. Add the eggs one at a time, mixing after each addition until fully incorporated, then add vanilla and lemon zest.
In another bowl, combine almond flour, rice flour, oat flour, sugar, baking soda, baking powder, and salt. Add about half of the dry mixture to the wet ingredients and mix to combine.
Add the sour cream and mix until incorporated. Then add the remaining dry ingredients and stir everything together.
In the prepared loaf pan, pour the batter and bake until a cake tester or toothpick inserted into the center comes out clean, it should be around 40–50 minutes.
Cool it in the pan for 15 minutes before unmolding onto a cooling rack. While the cake bakes, make the glaze and the syrup.
To make the glaze: In a medium bowl, whisk together the confectioner’s sugar, lemon juice, and cream to form a thick glaze.
The thick glaze should fall off the spoon in a thick drizzle. But, if it’s too thick, add more cream, one tablespoon at a time until the glaze reaches the desired consistency.
To make the syrup: Combine the lemon juice and sugar in a small saucepan and cook over low heat. Stir until the sugar dissolves then set aside.
When the loaf is still hot, prick holes in the top (with a toothpick or skewer) and immediately brush with syrup.
Finally, once the cake is sufficiently cool, drizzle the glaze over the top. Slice and serve with berries and whipped cream or yogurt! Enjoy!