1-First step: Gather and prep everything Set out your ingredients before you begin. Separate the eggs so you have 3 whole eggs, 3 yolks, and 3 reserved egg whites ready to go. Zest the lemon, squeeze enough juice to measure 0.5 cup, and measure out the sugar, salt, and cream. Having everything ready makes the process feel calm and keeps the mousse from overcooking while you search for ingredients.

2-Second step: Start the lemon custard base In a heat-proof bowl, whisk together 3 whole eggs, 3 egg yolks, 1 cup sugar, the lemon zest, lemon juice, and salt. Place the bowl over simmering water to form a double boiler. Stir constantly for about 15 minutes, until the mixture thickens and reaches 150°F, or 66°C. This slow heat is important because it cooks the eggs gently and keeps them smooth instead of scrambled. If your stove runs hot, keep the water at a gentle simmer rather than a hard boil. The bowl should sit above the water, not touch it. That steady warmth gives you a silky lemon base with no grainy bits.

3-Third step: Chill the cooked mixture Once the custard thickens, remove it from the heat. Cover the surface with plastic wrap pressed right against the mixture so a skin does not form. Chill for at least 2 hours. This step matters because a cold base helps the whipped ingredients hold their shape later. If you are planning ahead, this part can be made earlier in the day or even the night before.

4-Fourth step: Whip the egg whites In a clean bowl, beat the 3 reserved egg whites with the remaining 2 tablespoons sugar until stiff peaks form. The whites should look glossy and stand up when you lift the beaters. If you are nervous about overbeating, stop as soon as the peaks hold their shape. This airy egg white mixture gives the mousse its light lift. For the best fluffiness, fold the egg whites in gently instead of stirring them in. That keeps the mousse soft and cloud-like.

5-Fifth step: Fold everything together Take the chilled lemon mixture from the fridge. Gently fold in the whipped egg whites using a spatula. Next, whip the 0.5 cup heavy whipping cream to stiff peaks and fold that in too. If you want extra lemon flavor, fold in the optional 0.5 cup homemade lemon curd at this point. Work slowly and softly so you do not lose the air that makes the mousse light. Use a folding motion rather than a stirring motion. That means cutting down through the center of the bowl, scooping under the mixture, and turning it over on itself. A few careful turns are better than many rough ones. For another creamy citrus dessert idea, you may also like this silky lemon cream treat.

6-Final step: Portion, chill, and serve Spoon the mousse into individual cups or into one serving bowl. Chill for at least 30 minutes before serving, though a longer chill gives a firmer texture. Top with whipped cream or a spoonful of lemon curd if you like. This recipe makes about 3 cups total, and it is easy to portion into small dessert glasses for neat serving. If you want a sharper lemon flavor, you can slightly adjust the lemon juice next time. If your family likes sweeter desserts, keep the curd topping on the side so everyone can add their own amount. The beauty of Easy Fresh Lemon Mousse is that it can feel casual or polished depending on how you serve it.