Melt the butter and set aside to cool to room temperature.
In a large mixing bowl, beat the eggs, erythritol, and two tsp. of the grapefruit zest with an electric mixer (or ideally a stand mixer) until they are light, frothy, and at least doubled in volume. The whipped eggs should be the color of butter and the consistency of slightly whipped heavy cream. This will take about 10 minutes.
In a small bowl, mix the almond flour, Keto Chow, and baking powder and set aside.
When the eggs and erythritol are fully whipped, add the dry ingredients and gently fold in with a wooden spoon or rubber spatula.
Add the melted butter and gently fold into the mixture.
Allow the batter to rest for 10-20 minutes. While it rests, preheat the oven to 325℉.
Brush a thin layer of softened butter inside the madeleine molds.
Use a small (.75 oz, #40) cookie scoop to fill each mold with about 1 1/2 Tbsp. batter. It’s okay if the batter sits in the middle of the molds; it will spread to fill them when it bakes.
Place the filled tray in the center rack of the oven and bake for about 12-15, or until the cakes are golden around the edges and spring back when touched lightly in the center.
Madeleines can be enjoyed warm or cooled completely and dipped in white chocolate. To decorate with white chocolate, melt the chocolate and stir in a drop or two of pink food coloring.
Dip one edge of each madeleine into the melted chocolate and place on a rack to set. Sprinkle with extra grapefruit zest if desired.
Madeleines are best eaten within a day or two but can be stored tightly wrapped in the freezer up to three months.
Notes
*Using a silicone madeleine pan will not allow the batter to cook evenly.