Preheat the oven to 350 degrees F. Line a 9-inch square baking pan with foil.
In a large bowl, whisk the almond flour, all purpose flour, and sugar. Stir in the melted butter, mixing well to create a thick paste. Press the mixture firmly and evenly into the bottom of your lined pan. Bake for 14 minutes.
In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese. Add the sugar, lemon zest, and lemon juice and mix until combined. Add the egg and beat until smooth. Pour over the hot crust, pushing the batter to the sides of the pan and smoothing the top.
Bake until the center of the cheesecake is set (it’s OK if it has a slight jiggle to it since it will continue to cook after you take it out of the oven), 18 to 20 minutes. Let the bars cool on a wire rack for 30 minutes then refrigerate until thoroughly chilled before cutting and serving.