In a large mixing bowl, combine 2 cups of plain Greek yogurt and 1/2 cup of natural peanut butter. Blend thoroughly until smooth and creamy, about 1-2 minutes.

Gently stir in 1 teaspoon of vanilla extract. If desired, add 2 tablespoons of honey or pure maple syrup and mix for another minute.

Transfer the mixture into a loaf pan, smoothing the top evenly with your spatula.

Cover the loaf pan with aluminum foil or a lid and place it in the freezer for at least 4 hours, preferably overnight.

Remove the pan from the freezer, let it sit at room temperature for 5-10 minutes if too hard to scoop, then slice or scoop the bars.