Preheat the oven to 350°F. Wash and dry the fresh produce. Line a 9-inch cake pan with parchment paper (or lightly grease). Using a zester or the small side of a box grater, finely grate the lemon to get 2 teaspoons of zest (reserving the rest of the lemon to make the glaze). Melt the butter in a large bowl in the microwave (or melt in a small pot on the stove, then transfer to a large bowl). Let cool slightly.

In a medium bowl, combine the biscuit mix, flour, and a pinch of salt. Whisk to thoroughly combine. To the bowl of melted butter, add the granulated sugar, vanilla powder, sour cream, eggs, lemon zest, honey, and 3 tablespoons of water. Whisk until smooth. Add the dry ingredients to the wet ingredients. Stir until just combined (be careful not to overmix). Gently fold in the blueberries. Transfer to the prepared pan; spread into an even layer. Bake 22 to 26 minutes, or until the cake is set and cooked through. Remove from the oven and let cool about 1 hour, or until room temperature (for quicker cooling, place in the refrigerator).

Meanwhile, quarter and deseed the lemon. In a bowl, combine the powdered sugar and the juice of 4 lemon wedges. Whisk to combine, then gradually add 1 teaspoon of water at a time to achieve your desired consistency. Top the cooled cake with the glaze; cut into equal-sized pieces. Enjoy!