1. Position rack in lower third of the oven; preheat to 350°F. Liberally butter a 2-quart, 2-inch deep baking dish.
2. To make the topping: Combine all ingredients in a bowl and mix well. Set aside.
3. To make the filling: Combine orange zest, juice, and chopped apricots in small bowl. Let apricots soften while you prepare apples. Mix sugar and cinnamon in large bowl. Quarter and core the apples. Cut each quarter into 3 or 4 chunks. Toss the apples with the cinnamon sugar. Stir in the apricots and juice.
4. Scrape the mixture into the buttered baking dish and spread it evenly. Distribute the crumbly topping evenly over the apples. Bake for 1 1/4-1 1/2 hours, until the crisp is browned on top and the juices are bubbling and thickened. (If your apples were a little dry, you may not see any juices toward the end of the baking time; if so, the browned topping is your cue to doneness.) Serve warm or cold. Top with ice cream or frozen yogurt, if desired.