Lemon Curd

Fill 1-2 inches of water into saucepan. Place on high until it boils, and then reduce to low to keep it simmering.

Put a glass heat-safe bowl on top of your saucepan - it should fit without falling in. Place yolks, sugar, lemon zest, lemon juice, and salt into the bowl, whisking until blended. Whisk and cook until the mixture thickens up, ~10 mins. If it's not thickening, turn up the heat. Whatever you do, don't stop whisking.

Butter should be softened. With your curd removed from the heat, whisk the butter into the curd. Add plastic wrap that touches the top of the curd to prevent a skin from forming. Let cool.