Step 1: Mixing the Ingredients

Start by selecting a large microwave-safe bowl—bigger than you think you need. The lemon curd will expand as it cooks, and a smaller bowl may lead to messy spills.

1. Whisk together the melted butter and granulated sugar in the bowl. The sugar should dissolve slightly as you mix.
2. Add the eggs and extra yolk, whisking thoroughly until the mixture is completely smooth.
3. Pour in the lemon juice and zest, continuing to whisk until fully combined. The mixture will look thin at this stage, but don’t worry—it will thicken as it cooks.

Step 2: Cooking in the Microwave

Now comes the easiest part—cooking the curd in the microwave.

1. Set your microwave to high power and cook the mixture in 1-minute increments. After each minute, remove the bowl and stir the mixture thoroughly. This ensures even cooking and prevents the eggs from scrambling.
2. Continue microwaving and stirring in 1-minute intervals until the curd thickens enough to coat the back of a spoon. This usually takes about 5 minutes, but times may vary based on microwave wattage.
3. Watch closely to prevent overheating, which can cause the curd to curdle or bubble over.

Step 3: Straining for a Silky Texture

Once the curd reaches the right consistency, remove it from the microwave and pour it through a fine mesh strainer into a clean, heat-safe container. This step removes any tiny egg bits and ensures a perfectly smooth, silky texture.

To prevent a skin from forming, press a piece of plastic wrap directly onto the surface of the curd. Let it cool completely before transferring it to the refrigerator.