Apple Crisp with Prune Tequila Ice Cream

Name: Apple Crisp with Prune Tequila Ice Cream
Ingredients: 2 1/3 cups all-purpose flour; 3/4 cup packed dark brown sugar; 1/4 cup granulated sugar; 3/8 teaspoon cinnamon; 3/8 teaspoon salt; 2 sticks (1 cup) unsalted butter, cut into tablespoon pieces and softened; 1 1/3 cups pecans, toasted and chopped; 1/2 cup granulated sugar; 1/2 teaspoon cinnamon; 5 pounds Macoun, Fuji, or Jonagold apples; 2 tablespoons fresh lemon juice; Finely grated zest of 1 navel orange; Accompaniment: prune tequila ice cream