First, preheat oven to 325 degrees.
Second, line a loaf pan with parchment paper and spray with nonstick cooking spray.
Third, in a large mixing bowl combine the wet ingredients: butter, sugar, eggs, lemon juice, lemon zest, and vanilla extract with a hand mixer on medium speed until smooth and creamy.
Next, in a separate bowl, add the dry ingredients: gluten-free flour, baking powder, and salt, and mix well.
Then, add to the wet ingredients and mix until smooth.
Pour the cake batter into the prepared loaf pan. (Don't forget to scrape down the sides of the bowl with a spatula. We don't want to waste any of this goodness.)
Bake for 40-45 minutes or until the center of the cake is set. (You can check this with a toothpick.)
After the cake is finished baking, remove from the oven and let the cake cool completely on a cooling rack (wire rack) before pouring the lemon glaze on top.
While the cake is cooling, it's time to make the glaze.
In a small bowl, combine the stevia, lemon juice, cornstarch, and water and mix until smooth.
Finally, pour the lemon glaze on top of the room-temperature cake, cut into thick slices, and enjoy!