Preheat the Oven: Preheat your oven to 350°F (175°C).
Prepare the Lemon: Cut the lemon into sections and remove the seeds. Place the lemon sections into the blender.
Blend the Ingredients: Add the eggs, melted butter, sugar, and vanilla extract (if using) to the blender with the lemon. Blend until the mixture is smooth.
Pour into Crust: Pour the blended lemon mixture into the unbaked pie crust.
Bake the Pie: Bake in the preheated oven for about 45 minutes, or until the filling is set and the top is lightly golden.
Cool and Serve: Let the pie cool completely before serving. Chill in the refrigerator for at least 2 hours for a firmer texture. Dust with powdered sugar and garnish with lemon slices if desired.