Peel and dice plums, place in a small saucepan. Stir in 1/2 teaspoon cinnamon, 2 Tablespoons sugar, and the water. Bring to a boil over medium heat. Lower heat to a simmer, and cook until mixture starts to thicken, stirring frequently. Cook about 5-10 minutes. Remove from the heat and allow to cool completely.

Preheat oven to 350 degrees F. Line baking sheets with parchment paper, silpat mat, or use baking stones.

In a medium size mixing bowl, whisk together the flour, cream of tartar, soda, and salt: set aside.

In a large mixing bowl, using an electric mixer, beat together the butter and 1 1/2 cups sugar until fluffy. Add the eggs and Fiori Di Sicilia; beat until smooth and well combined. Fold in the plum mixture.

Gradually beat in the flour mixture, in 3 parts, beating only until combined, scraping sides of the bowl.

Combine the remaining sugar and cinnamon in a small bowl.

Shape dough into 1 1/2 inch balls, using a small scoop or spoon. Roll each ball in the cinnamon-sugar mixture and place on baking sheets. Bake for 9-11 minutes or until edges are light golden brown. Remove cookies from the oven and allow to set on pans about 5 minutes. Transfer cookies to a wire cooling rack.

Prepare the glaze by stirring together the confectioner sugar, mascarpone cheese and 1 Tablespoon of the cream. Add more cream as needed to obtain a consistency to drizzle. Drizzle the glaze over over the cooled cookies. Add sprinkles if desired.

Arrange on serving platter or allow glaze to dry before storing.