FOR DOUGH: In a bowl, whisk together flour, baking powder and salt. In the bowl of an electric mixer fitted with the paddle attachment, beat butter and granulated sugar on medium speed until well combined, about 3 minutes. Add egg yolks, vanilla and zest; beat until well combined. Reduce speed to low. With mixer on low speed, add flour mixture, and beat until just combined.

Turn out dough onto a lightly floured work surface, divide in half and shape into flattened discs. Wrap discs separately in plastic and chill at least 1 hour or overnight.

Remove 1 disc dough from refrigerator; let stand until slightly softened. On a large piece of parchment paper lightly dusted with flour, roll out dough to scant 1/4-inch thickness, dusting with more flour if necessary to prevent sticking. Transfer parchment paper and dough to a baking sheet; freeze until firm, about 20 minutes. Repeat with remaining dough (parchment sheets and dough can be stacked).

Heat oven to 325º with racks in middle and upper third. Line 2 baking sheets with parchment paper. Working quickly and using 2 1/2-inch cutter, cut out rounds. Using 1 1/2-inch cutter, cut out center from half of rounds (dough can be returned to freezer if it begins to soften too much). Using a wide metal spatula, transfer cookie round and rings to prepared baking sheet, about  3/4inch apart; freeze until firm, about 15 minutes. Reroll scraps once (including cut-out centers), repeating same instructions. Repeat with remaining dough. (Cut-out centers from second rollout can be baked for bite-sized cookies. Baking time will
be the same.)

Bake cookies, rotating sheets halfway through, until lightly golden on bottoms, about 15 minutes. Transfer cookies to wire racks to cool completely. (Cooled cookies can be stored overnight in airtight container at room temperature before filling.) Meanwhile, make jam.

FOR JAM: In a medium skillet, combine strawberries, butter and granulated sugar. Heat over medium heat, stirring frequently, until jam forms and is slightly thickened, about 18 minutes. Transfer to a wide shallow bowl and let cool completely (jam will further thicken as it cools).

Spread flat sides of cookie rounds with scant  1/2 tablespoon jam. Dust cookie rings with confectioners sugar, then top rounds with rings. Repeat with remaining cookies. Top open rings with extra jam just before serving. (Once filled, cookies are best eaten the same day.)