Linzer cookies are crisp sandwich cookies with a shape cut out of the top cookie that reveals a bright red, shiny raspberry filling. If you don't have Linzer cookie cutters, use a 2-inch circle cutter for the bottom cookies. For the top cookies, cut out 2-inch circles and then cut out a 1/2-inch shape from the enter of each cookie. The baked cookies will stay fresh for at least 4 days in an air-tight container separated by wax or parchment paper.
1. In medium bowl combine oat flour, wheat flour, almond meal and salt.
2. In large mixer bowl beat butter and cane sugar on medium-high speed of electric mixer about 1 minute or until well combined. Add egg yolk and vanilla. Beat until fluffy. Add flour mixture. Beat on low speed until just combined.
3. Shape dough into a ball. Wrap in plastic wrap. Refirgerate for 30 minutes to 2 days.
4. On lightly floured surface roll dough, half at a time, to 1/8-inch thickness. (Dough will be sticky. Add flour to surface and rolling pin frequently.) Use Linzer cookie cutters to cut out cookies, rerolling scraps, as necessary. Place on baking sheet lined with parchment paper or slicone mats. Bake at 350° F about 9 minutes or until light golden brown around edges. Let stand on baking sheet for 2 minutes. Transfer to wire cooling rack. Cool completely.
5. Spread jam on solid cookies. Place cookies with center holes on top, so that the jam shows through.