How to Make It
Preheat oven to 350°F. Stir together cherries, granulated sugar, and lemon juice in a large saucepan. Cook over medium-high, stirring often, until cherries soften and release liquid, about 15 minutes. Pour mixture into a colander set over a bowl; let drain 20 minutes.
Transfer drained cherries to a large bowl; reserve strained juice for another use. Stir in amaretto, almond extract, and salt. Sprinkle cornmeal in an even layer over bottom of frozen pie shell; pour cherry mixture evenly into prepared pie shell. Bake in preheated oven until crust is light golden brown, about 35 minutes.
While pie bakes, stir together oats, flour, and brown sugar in a bowl. Add butter; using your hands, incorporate butter until mixture resembles small peas.
Remove pie from oven; sprinkle with oat mixture. Return to oven; bake at 350°F until topping and crust are golden brown, about 20 minutes. Transfer to a wire rack to cool completely, at least 4 hours or up to overnight.