Combine cherries and sugar in a large saucepan; cook over medium heat, stirring constantly, 15 minutes or until cherries are soft.
Dissolve cornstarch in water; blend well. Add to cherry mixture; bring to a boil. Reduce heat; cook, stirring constantly, until mixture is thickened and bubbly. Remove from heat, and stir in butter and almond extract. Cool. Spoon 2 teaspoons cherry filling into each tart shell.