Preheat your oven to 350°F (175°C). Grease a 9x9-inch baking dish with cooking spray or line it with parchment paper for easy removal later.
In a medium bowl, combine graham cracker crumbs, melted butter, and 1/4 cup granulated sugar. Mix until well combined and crumbly.
Press the crumb mixture firmly into the bottom of the prepared baking dish to form an even crust. Bake in the preheated oven for 10 minutes, then remove and let cool slightly.
In a large mixing bowl, whisk together the Greek yogurt, fresh lemon juice, 1 cup granulated sugar, eggs, lemon zest, and vanilla extract until you have a smooth mixture.
Pour the lemon filling over the cooled crust, spreading evenly.
Bake for an additional 25-30 minutes, or until the filling is set and only slightly jiggles in the center.
Remove from the oven and allow to cool to room temperature, then refrigerate for at least 2 hours to fully set.
Once chilled, dust the top with powdered sugar, then slice into bars.
Notes
Arrange the lemon bars on a decorative platter, and garnish with fresh lemon slices or mint leaves for an extra touch.