Vegan Meyer Lemon Poppyseed Shortbread

Name: Vegan Meyer Lemon Poppyseed Shortbread
Ingredients: 1 2/3 cup gluten-free flour blend (267g); 1/3 cup almond flour (40g); 1/3 cup cornstarch (45g); 1/2 teaspoon sea salt; 1 cup vegan butter, softened (225g); 1/2 cup cane sugar (100g); 2 meyer lemons (or lemon + orange); 1/2 teaspoon vanilla extract (2.5mL); 1/2 teaspoon pure lemon extract, optional (2.5mL); 3/4 cup powdered sugar (75g); 1 1/2 tablespoon meyer lemon juice (22mL); 1 tablespoon poppyseeds; 1 tablespoon vegan butter, melted (14g)