PreparationFOR COOKIES: Mix flour, salt and baking powder in medium bowl. Using electric mixer, beat butter in large bowl until light. Gradually beat in sugar. Beat in egg, then poppy seeds, lemon peel and extracts. Mix in dry ingredients in 3 additions. Gather dough into ball. Divide dough in half; flatten each half into disk. Wrap in plastic; chill 2 hours. Preheat oven to 325°F. Butter 2 large baking sheets. Roll out 1 dough disk on floured surface to 1/8-inch thickness. Using 21/2-inch-diameter fluted cookie cutter, cut out cookies. Arrange cookies 1 inch apart on prepared baking sheets. Gather scraps; reroll and cut out more cookies. Chill cookies on baking sheets 15 minutes. Bake cookies until edges just begin to color, about 18 minutes. Cool cookies on sheets 3 minutes. Transfer cookies to racks; cool completely. Repeat rolling, cutting and baking with remaining dough. (Can be made ahead. Store in airtight container at room temperature up to 2 weeks or freeze up to 1 month.) FOR FILLING: Beat all ingredients in large bowl until light and fluffy. Spread 2 teaspoons filling over bottom of 1 cookie. Press second cookie, bottom side down, onto filling. Repeat with remaining cookies and filling. (Can be made 2 hours ahead. Cover and chill.)
PreparationFOR COOKIES: Mix flour, salt and baking powder in medium bowl. Using electric mixer, beat butter in large bowl until light. Gradually beat in sugar. Beat in egg, then poppy seeds, lemon peel and extracts. Mix in dry ingredients in 3 additions. Gather dough into ball. Divide dough in half; flatten each half into disk. Wrap in plastic; chill 2 hours. Preheat oven to 325°F. Butter 2 large baking sheets. Roll out 1 dough disk on floured surface to 1/8-inch thickness. Using 21/2-inch-diameter fluted cookie cutter, cut out cookies. Arrange cookies 1 inch apart on prepared baking sheets. Gather scraps; reroll and cut out more cookies. Chill cookies on baking sheets 15 minutes. Bake cookies until edges just begin to color, about 18 minutes. Cool cookies on sheets 3 minutes. Transfer cookies to racks; cool completely. Repeat rolling, cutting and baking with remaining dough. (Can be made ahead. Store in airtight container at room temperature up to 2 weeks or freeze up to 1 month.) FOR FILLING: Beat all ingredients in large bowl until light and fluffy. Spread 2 teaspoons filling over bottom of 1 cookie. Press second cookie, bottom side down, onto filling. Repeat with remaining cookies and filling. (Can be made 2 hours ahead. Cover and chill.)