The day before you plan to bake, combine sugar and lavender buds in a jar. Close the lid and shake well. Leave overnight to let the sugar infuse.
Strain sugar through a mesh strainer to remove lavender. Set aside buds for garnish (optional).
Heat oven to 350°F. Line an 8" square baking dish with parchment and set aside.
In a medium bowl, whisk together 1/4 cup of the lavender infused sugar and 1 cup of the flour.
Melt butter in a microwave-safe dish. Pour over flour mixture and stir to combine. Press mixture into the bottom of the prepared baking dish. Bake 12-15 minutes.
While crust is baking, whisk together remaining 1 cup lavender infused sugar, remaining 2 tsp flour, baking powder and salt in a large bowl. Add the lemon zest and rub it into the sugar mixture with your hands for a more pronounced lemon flavor.
Add eggs and lemon juice. Whisk well for 1 minute, or until light and fluffy.
Pour mixture over baked crust (no need to cool). Bake for an additional 21-25 minutes.
Cool completely. Dust with powdered sugar and sprinkle with lavender buds (optional). Slice into bars.
Line your baking dish with parchment for easy removal from the pan and cutting.
Make sure the bars are completely cooled before adding powdered sugar and cutting. If they're still warm, the sugar will just melt on the top.
For gluten-free lemon bars, use your favorite cup-for-cup gluten-free flour in place of all purpose flour.
For a more pronounced lavender flavor, use 2 tbsp lavender buds in the sugar. For a lighter flavor, use just 1 tbsp.
Store leftover lemon bars in an airtight container in the refrigerator.