Preheat The Oven to 350 degrees F. Set aside your bundt pan, oil/spray oil, and 2 Tablespoons sugar for greasing the pan later. (Don't prep the pan now, just have everything ready)

Combine The Dry Ingredients. In a medium bowl, combine gluten-free flour blend, cornstarch, baking powder, baking soda, and salt. Whisk to combine and set the dry ingredients aside.

Rub Lemon Zest Into The Sugar. Zest the lemons (measuring a full 1/4 cup!), and place the zest in the bowl of a stand mixer with the sugar. Use your fingertips to rub the zest into the sugar. It should smell fragrant and the sugar should be moist and slightly yellow from the zest.

Squeeze Lemon Juice Into The Milk. Then, squeeze 1/4 cup lemon juice and add it to the milk. Whisk to combine and set aside. (This mixture will start to thicken and curdle a bit--this is normal!)

Cream Butter & Sugar. Add the softened butter to the mixer with the lemon sugar and cream 2-3 minutes on medium speed until light and fluffy.

Add Eggs, One At A Time to the mixer, beating to incorporate each egg before adding the next one.

Mix In The Sour Cream & Flavorings. Add sour cream, vanilla extract, almond extract, and lemon oil/lemon extract to the mixer. Mix until combined.

Alternate Dry Ingredients & Milk. Then, add half of the dry ingredients. Quickly pulse the mixer to combine a bit (this helps avoid the dry ingredients poofing out!), then mix until almost fully incorporated. Add half of the milk/lemon juice mixture and mix to combine. Scrape down the edges and repeat, adding the second half of the dry ingredients, mixing until almost incorporated, then pouring in the second half of the milk mixture and mixing till just combined.

Prep Your Pan. Working quickly, spray or brush the bundt pan well with oil, making sure to get all of the curves, dips, and indents, and the center tube. Sprinkle 2 Tablespoons of sugar into the pan evenly then tap the sides of the pan to distribute the sugar. Tap out any excess sugar by turning the pan upside down to let excess sugar fall out.

Pour The Batter Into The Prepared Pan and smooth into an even layer.

Bake The Cake for 45-55 minutes (the exact time will be different based on your pan materials, shape, and size). The top should spring back when gently pressed, and a toothpick inserted in the center of the cake should come out clean with just a few moist crumbs. If you have an instant-read thermometer, the center of the cake should be between 200-210 degrees. 

While The Cake Bakes, Mix Your Lemon Syrup. In a small microwave-safe bowl, combine 1/2 cup sugar and 1/3 cup lemon juice. Whisk to combine, then microwave in 20-30 second increments, stirring in between each interval, until the sugar is fully dissolved.

Let The Cake Cool 10 Minutes before turning out onto a wire rack to finish cooling. (I put the cooling rack on top of the cake in the pan like a lid, then use oven mitts to flip the cake and rack upside down so that the rack is now on the bottom and the cake can fall out onto the rack.

Brush With Lemon Syrup. Right after you turn the cake out of the pan, brush the cake with lemon syrup, doing your best to evenly brush it around the sides cake and into the center. (It'll seem like way too much, but it soaks in and locks moisture into that cake--use it all!)

Once the cake is completely, totally cool (not even a little warm!), you can mix up your glaze.

Combine powdered sugar, 2 Tablespoons milk, 1 Tablespoon lemon juice, and 1/2 teaspoon of vanilla.

Whisk to combine until it becomes a very thick glaze. (Mix for 1-2 minutes before adding any additional liquid, then only add 1/2 teaspoon at a time, until you reach a very thick but pourable consistency.)

Pour the glaze over the cooled cake and let it set before slicing with a knife. 

Store. This cake will keep covered at room temperature 2-3 days, or you can wrap slices in plastic wrap and place them in an airtight container or freezer bag in the freezer up to 1 month.