01 -
In a large mixing bowl, blend all-purpose flour, baking powder, and powdered sugar until evenly combined.
02 -
Melt salted butter in the microwave or a saucepan. Introduce the melted butter and vanilla extract to the dry mixture. Mix thoroughly until a smooth dough forms. Cover and refrigerate for 30 minutes.
03 -
Wash, drain, and weigh the mulberries. Process briefly in a food processor, then combine in a saucepan with granulated sugar (using a 2:1 fruit-to-sugar ratio). Bring to a boil over medium-high heat and cook for 5 minutes. Lower the heat, reduce the mixture by half, then incorporate lemon juice and lemon seeds. Continue simmering until the jam thickens. Discard lemon seeds after cooking.
04 -
Preheat oven to 175°C. Line a baking sheet with parchment. Portion the chilled dough into balls of roughly 1 tablespoon each and arrange on the tray, ensuring adequate spacing. Press a thumbprint into each ball to form a well.
05 -
Spoon approximately 1 teaspoon of prepared mulberry jam into the center of each cookie. Avoid overfilling to prevent spillage during baking.
06 -
Bake for 12 to 15 minutes, or until golden at the edges. Let rest on the tray for 2 minutes, then transfer to a wire rack to cool completely.