Preheat the oven to 325F and coat a square 8×8 dish with nonstick spray and line all 4 sides with parchment paper, allowing it to hang over the edges of the pan for easy release.

Trace a square outline of the pan on a separate sheet of parchment paper and set aside.

In a medium bowl, whisk together the salt, almond flour, and flour. Set aside.

In a large mixing bowl, using a hand or stand mixer with the paddle attachment, mix together the butter and sugar. Start on a low speed then slowly work your way up to prevent the sugar from flying out of the bowl.

Once smooth and fluffy, mix in the egg and vanilla.

Switch to a rubber spatula, add in the dry ingredients and mix by hand until combined. The consistency should be similar to mashed potatoes.

Scoop half of the dough into the prepared baking pan and spread it even.

With the other half of the dough, spread it onto the sheet of parchment paper that we outlined earlier.

In bowl, combine all of the filling ingredients. It should resemble wet sand.

Crumble and lightly press an even layer of the filling on top of the shortbread dough that’s inside the pan.

Then carefully flip the parchment paper dough on top of the filling layer and peel back the paper.

Once all the paper is peeled back, the top layer of dough won’t be perfect so spread it as even as possible.

Bake the shortbread for 40-45 minutes or until it’s evenly puffed and the edges are a light golden brown.

Let the shortbread rest at room temperature for 30 minutes, then transfer to the refrigerator to chill uncovered for about an hour.

Once the bars have chilled, make the icing by whisking together all of the icing ingredients, starting with just 1 tablespoon of milk.

If the icing appears too thick, mix in the additional tablespoon.

Spread the icing on top of the shortbread as soon as you’re done mixing it.

Top with a light sprinkle of sea salt, slice, and enjoy!