1cupall-purpose flour126 g, measured using a spoon and level method
3/4packedbrown sugar(light or dark), lightly-packed
2/3cupold fashioned (rolled) oats
8tablespoonsunsalted butter, cubed and softened (plus additional for greasing the pan)
1tablespoonfresh lemon juice
1/4cupbrown sugar, lightly-packed
Preheat oven to 350 degrees F. Lightly butter a 9x9 inch baking dish with at least 2-1/4 inch sides. Place on a foil-lined baking sheet.
Make the Crisp Topping
In a medium bowl, whisk together flour, baking powder, cinnamon, salt, brown sugar, and oats. Using a fork, pastry blender, work the butter into the dry ingredients until a crumbly mixture forms. The topping should hold together in clumps when pressed. Set aside while you prepare the filling.
Prep the Filling
Peel, core, and slice apples 1/4-inch thick. In a large bowl, toss apple slices with lemon juice, bourbon, flour, cinnamon, nutmeg, salt, granulated sugar, and brown sugar until evenly coated.
Assemble and Bake the Crisp
Evenly spread the apples into the prepared baking dish. Top with the oat streusel. Bake for 45-60 minutes, until apples are tender, the topping is browned, and the filling is bubbling both in the corners and the center of the pan. (Baking time will depend on the apples you used, the pan, and your oven.)
Watch the crisp while it's baking to ensure that the topping isn't browning faster than the apples are cooking. I like to start checking around the 30-minute mark. If you see that the topping is browning quickly, loosely cover the pan with a piece of foil, uncovering during the last 5-8 minutes of baking.
Let the crisp cool for at least 20-25 minutes before serving so the juices thicken. Serve warm with ice cream or whipped cream, and a drizzle of caramel sauce, if desired.
See the "Apple Varieties" section in the article above for alternate apple recommendations.If you're using a sweeter apple variety than Honeycrisp, or prefer a less sweet crisp, you might enjoy reducing the sugar in the filling to 2 tablespoons granulated and 2 tablespoons brown.If you're using a very tart baking apple, or prefer a very sweet crisp, you might enjoy increasing the sugar in the filling to 1/3 cup granulated and 1/3 cup brown.