Line an 8-inch square baking pan** with parchment paper, letting ends extend over edges of pan. Spray lightly with cooking spray.
In a large mixing bowl, beat together butter, confectioners’ sugar, brown sugar, lemon zest, lemon extract, and vanilla extract at medium-high speed with a mixer until light and creamy, 2 to 3 minutes.
In a medium bowl, whisk together flour, lavender, and salt until combined. Add to butter mixture, beating until incorporated. Press dough into prepared pan. (Use a latex glove or lightly dampen hands with water to prevent dough from sticking to hands, if desired.)
Bake until edges of shortbread are golden brown and a wooden pick inserted in center comes out clean, 45 to 50 minutes. Using the blunt end of a bamboo skewer, press holes into warm shortbread at even intervals. Let shortbread cool completely in pan on a wire rack.
Using parchment paper as handles, carefully lift shortbread from pan. Transfer shortbread to a cutting surface. Using a large sharp knife and pressing downward to create clean cuts, trim and discard rough edges. Cut into 16 squares.
Garnish serving platter with fresh lavender flowers, if desired.
Notes
* We used lavender from Gourmet Sweet Botanicals, 800-931-7530, gourmetsweetbotanicals.com.
**We used Wilton Perfect Results.
Recipe by TeaTime Magazine at https://teatimemagazine.com/lemon-lavender-shortbread/