Lemon Poppy Seed Shortbread Sandwich Cookies

These lemon Poppy Seed Shortbread Sandwich Cookies with Lemon Buttercream are rich and buttery. Full of lemon zest, lemon juice, and poppy seeds. Rich shortbread cookies are sandwiched together with creamy lemon buttercream. These sandwich cookies are perfectly bite sized and require only 30 minutes of chill time.