For the sprinkle:
1 tablespoon (12 grams) sugar
1/2 teaspoon (2 grams) cinnamon

For the cookie bars:
1 1/4 cup (156 grams) flour
1/2 teaspoon (2 grams) baking powder
1/2 teaspoon (2 grams) baking soda
1/2 teaspoon (2 grams) salt
1/2 teaspoon (2 grams) cinnamon
4 tablespoons (56 grams or half a stick) butter, melted
1/2 cup (110 grams) sugar
1/2 cup (115 grams) brown sugar
1 teaspoon (5 ml) vanilla
2 eggs
1/2 cup (133 grams) speculoos cookie butter*

For the frosting:
2 tablespoons (28 grams) butter, very soft
generous 1/3 cup (about 90 grams) speculoos cookie butter*
2 cups (250 grams) powdered sugar
5 tablespoons (74 ml) half and half or heavy cream, plus more as needed