Preheat the oven to 325 degrees F (165 degrees C).

Make the tart shells: Sift flour and confectioners’ sugar into a bowl. Cut in butter, then knead until well blended. Form dough into forty-eight 3/4-inch balls. Place one ball into each cavity of two 24-cup mini muffin tins. Press balls into the bottom and up the sides of each cup to form a shell.

Bake in the preheated oven until pale gold, about 16 minutes. Remove from the oven and let cool in the pans. Use a knife to gently loosen and remove cooled tarts from the pan.

While the tarts are baking, make the filling: Combine dates, water, brown sugar, and salt in a saucepan. Bring to a boil; boil gently for about 10 minutes, stirring constantly and mashing dates with a fork as they cook. Remove from the heat and stir in vanilla. Allow filling to cool.

While the filling is cooling, make the icing: Cream butter in a small bowl with an electric mixer. Gradually add 1 cup confectioners’ sugar while continuing to mix. Add remaining sugar, milk, and maple extract; beat on high speed until smooth and thick enough to pipe. Spoon icing into a pastry bag fitted with a small round or star-shaped tip.

Spoon filling into tart shells. Pipe a swirl of icing onto each tart.