Grate the Meyer lemons, taking care to exclude the white pith, until you have 1/2 teaspoon of zest. Slice and squeeze the lemons to produce 1/2 cup of lemon juice, straining as you go to catch the seeds. (I had really small, lime-sized lemons, and I needed 5.)
Heat a medium, heavy-bottom sauce pan over low, and add the lemon juice, sugar, egg yolks, eggs, and salt, and whisk well, until the egg yolks have smoothed out (the mixture will still appear broken - that's okay). Add the lemon zest, the rosemary, and the butter, and stir constantly until the butter melts (this will take several minutes). The butter will emulsify the lemon and eggs, creating a smooth, golden solution.
Increase heat to medium-low. Stir constantly to prevent the eggs from setting up. Keep stirring until the mixture thickens and begins to resemble a creamy jelly. This will take 5 to 10 minutes. If you have an instant read thermometer, you're looking for the curd to reach 170°F. The curd should fall - not drip or drizzle - from the whisk or spatula when lifted.
Remove the rosemary sprigs (it's okay of leaves have fallen off the stem) and strain the curd through a fine mesh strainer over a bowl. (Use a spatula to push the mixture through the mesh.) Let the curd cool. (Accelerate the cooling process by placing the bowl in a larger bowl half-filled with ice water.)
Refrigerate the curd for up to 2 weeks. To enjoy with yogurt, mix in a spoonful.
Meyer lemons - a cross between oranges and lemons - are sweeter than regular lemons. If using regular lemons, up the sugar to about 1/2 cup to compensate for the tartness.
Meyer Lemon Curd with Rosemary: A Yogurt Mix-in was originally published on https://soupaddict.com/meyer-lemon-curd-rosemary/