Pull the butter from the refrigerator and set aside to warm slightly. Zest a lemon to get ½ tsp zest and then juice it to get 1 tbsp juice. Dump the blueberries into a small saucepan, add 1 tbsp granular sweetener and the lemon juice and zest. Give it a stir, bring it to a simmer and cook for 8 minutes. Using an immersion blender, puree the blueberry sauce until smooth, then set aside to cool.
Heat oven to 350° and line an 8x8" baking dish with parchment paper. Add the butter to a mixing bowl and cream with the electric hand blender until all lumps are gone. Add the golden sweetener and blend until smooth. Mix in the vanilla and sea salt until fully combined.
Dump the almond flour into the mixing bowl and blend on low with the hand blender, just until the almond flour is barely mixed in. This should create coarse crumbles. Do not over mix!
Take a little over half of the dough and sprinkle into the bottom of the baking dish. Press down lightly to firm the dough into place, and then pour the blueberry sauce evenly over the surface of the crust.
Take the rest of the crumbled dough and spread it out evenly over the blueberry sauce. Sprinkle the sliced almonds over the surface and then bake in the preheated oven for about 25 minutes, until the top of the Keto Blueberry Bars are golden.
Remove from the oven and cool until room temperature, then refrigerate until firm, about 2 hours. Slice into 12 and enjoy!