These yummy bars are great for lunches or potlucks.
Preheat oven to 350 degrees. Butter an 8-inch square baking dish. In a bowl, whisk together flour, cinnamon, salt, and baking powder.
In a mixing bowl, cream butter and sugars on high speed until light and fluffy; beat in egg yolk. Reduce speed to low; gradually mix in flour mixture. Stir in almonds. In a small bowl, whisk jam to loosen. (Stirring the jam with a fork or a whisk will enable it to spread smoothly over the dough.)
Gently press half of dough into bottom of prepared dish. With the back of a spoon, gently spread jam over dough, leaving a 1/4-inch border so the jam doesn't stick to the sides of the pan. Sprinkle remaining dough over top all the way to the edges; press gently to form top layer.
Bake until top is golden, 25 to 35 minutes; cool completely in dish. Cut into bars with a serrated knife.