Preheat your oven to 325F and line an 8x8-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
Mix the almond flour, melted butter, powdered erythritol, and salt together until crumbly. Press firmly and evenly into the bottom of the prepared pan. Bake for 10 minutes until lightly golden, then remove and let it cool while you prepare the filling.
In a small cup, whisk the matcha powder with the hot water until completely dissolved and smooth with no lumps. Set aside.
Beat the cream cheese and powdered erythritol in a large bowl with an electric mixer on medium speed until smooth and creamy, about 2 minutes. Add the sour cream and vanilla extract and beat until combined.
Add the dissolved matcha paste and mix on low speed until the batter turns a uniform vibrant green. Beat in the eggs one at a time, mixing just until each is incorporated. Do not overbeat once the eggs are added.
Pour the filling over the cooled crust and smooth the top with a spatula. Bake for 28 to 32 minutes until the edges are set and the center has a very slight jiggle.
Let the bars cool to room temperature in the pan, then refrigerate for at least 4 hours or overnight. Use the parchment overhang to lift out, then slice into 12 bars.
