In a small saucepan, whisk together the egg, fresh lemon juice, lemon zest, and sugar over low heat. Continue stirring constantly for about 5 minutes, until the mixture thickens and coats the back of a spoon. Remove from heat and stir in butter until melted. Allow the lemon curd to cool before transferring to a jar.

In a mixing bowl, add rolled oats, your choice of milk, Greek yogurt, chia seeds, honey, and vanilla extract. Stir well until all ingredients are fully combined.

In a mason jar, spoon in half of the oat mixture. Next, add a generous dollop of homemade lemon curd. Top with the remaining oat mixture, ensuring careful layering.

Cover the mason jar tightly and place it in the refrigerator for at least 4 hours or overnight.

Once chilled, remove the jar from the refrigerator and top with granola, extra lemon zest, or a drizzle of honey before serving.