Preheat your oven to 175°C (350°F) and line a square baking dish with parchment paper, leaving some overhang on the sides so you can easily lift the brownies out later without breaking them.

In a medium mixing bowl, add the almond flour, powdered sweetener, baking powder, and salt, then whisk everything together thoroughly until the mixture looks uniform and completely lump-free—this step is important for a smooth, even texture.

In a separate larger bowl, crack the eggs and whisk them for about 30–40 seconds until they become slightly frothy, then pour in the melted butter, fresh lemon juice, lemon zest, and vanilla extract, continuing to whisk until the mixture looks smooth, glossy, and fully combined.

Slowly add the dry ingredients into the wet mixture in 2–3 batches, gently folding and stirring after each addition until just combined—avoid overmixing here, as it can make the brownies dense instead of soft and tender.

Pour the batter into your prepared baking dish and use a spatula to spread it evenly into all corners, smoothing the top so it bakes uniformly and gives you clean, even squares later.

Place the dish in the preheated oven and bake for 18–22 minutes, keeping an eye on it toward the end—the edges should look set while the center remains slightly soft; a toothpick inserted should come out with a few moist crumbs, not wet batter.

Remove the baking dish from the oven and let the brownies cool completely in the pan, allowing them to firm up properly—this step is crucial, so don’t rush it or they may fall apart when cutting.

While the brownies are cooling, prepare the glaze by mixing powdered sweetener with fresh lemon juice in a small bowl, stirring until you get a smooth, pourable consistency that’s not too thick or too runny.

Once the brownies are fully cooled, drizzle the glaze evenly over the top, letting it naturally spread or gently tilting the pan to cover more surface if needed, then allow the glaze to set for a few minutes.

Lift the brownies out using the parchment paper, place them on a cutting board, and slice into even squares using a sharp knife, wiping the blade between cuts for clean edges, and serve chilled or at room temperature for the best flavor and texture.