Pastry
2 cups (8 1/2 ounces) all-purpose flour
1 tablespoon sugar
1 teaspoon salt
1 cup (2 sticks or 8 ounces) unsalted butter, cut into pats
1 large egg
2 tablespoons (1 ounce) milk

1 additional large egg (to brush on pastry)

Cinnamon Filling (enough for 9 tarts)
1/2 cup (3 3/4 ounces) brown sugar
1 to 1 1/2 teaspoons ground cinnamon, to taste
4 teaspoons all-purpose flour
1 large egg, to brush on pastry before filling

Jam Filling
3/4 cup (8 ounces) jam
1 tablespoon cornstarch mixed with 1 tablespoon cold water

Alternate fillings: 9 tablespoons chocolate chips, 9 tablespoons Nutella or other chocolate-hazelnut paste or 9 tablespoons of a delight of your choice, such as salted caramel or a nut paste

To make cinnamon filling: Whisk together the sugar, cinnamon, and flour.

To make jam filling: Mix the jam with the cornstarch/water in a small saucepan. Bring the mixture to a boil, and simmer, stirring, for 2 minutes. Remove from the heat, and set aside to cool. Use to fill the pastry tarts.