Instructions

• Preheat the oven to 175°C / 350°F and place a rack in the middle position.
• Line a 9 x 6-inch pan with parchment paper, leaving an overhang on two sides for easy removal.
• In a large bowl, beat 4 large room-temperature eggs until frothy (about 1–2 minutes) using an electric mixer or a whisk.
• Add ½ cup / 120 g sour cream and ½ cup / 120 g very soft butter to the eggs. Blend with an electric mixer or food processor until smooth and combined, scraping down the bowl as needed.
• Add ¼ cup / 4 tbsp lemon juice and the zest of 1 lemon, then add ⅓ cup / 40 g powdered erythritol. Mix until evenly incorporated. Taste the batter and add more powdered erythritol if you want it sweeter (ingredient list allows adjusting to taste).
• In a separate bowl (or add directly), combine 2 cups / 200 g almond flour and 2 teaspoons baking powder. If using super-fine almond flour, use 2 tablespoons less almond flour before adding.
• Add the almond flour–baking powder mixture to the wet ingredients and mix on low speed or fold with a spatula until you have a smooth, uniform batter. Scrape the sides and bottom of the bowl to ensure everything is mixed.
• Transfer the batter into the prepared pan and spread it evenly with a spatula.
• Bake on the middle oven rack for 35–40 minutes, until the top is lightly browned and a skewer inserted into the center comes out clean.
• Remove the pan from the oven and cool completely on a wire rack before cutting or removing from the pan—almond flour cakes are fragile when hot but firm up as they cool.
• Use the parchment overhang to lift the bars from the pan, then cut into portions once fully cooled.