Measure flour, sugar and salt into the food processor. Pulse once to mix. Pulse in butter until mixture looks crumbly. Mix together yolk, water and extracts. Pulse in, until dough starts to clump (if mixture seems dry, pulse in up to 1 tablespoon water).
6 tablespoons cold unsalted butter, cut up
1/3 cup sugar
1 egg yolk
1 tablespoon cold water
1/4 teaspoon vanilla (plus 1 drop almond extract, optional)
1/8 teaspoon salt
1 cup flour
Cream butter and sugar, using an electric mixer. Mix together yolk, water, extracts and salt; beat in. Beat in flour.
Tart: Pat pastry into a 9-inch tart pan; follow a sweet tart recipe.
Cookies: Roll pastry into 12 balls. Roll each in sugar; set on a parchment-lined baking sheet. Bake at 375 degrees, 5 minutes. Press each ball with a pinky finger (or the back of a small oval measuring spoon) twice to form a heart-shaped indentation. Return to oven and bake until golden, about 10 minutes. While warm, fill heart with raspberry or strawberry jam