Preheat oven to 350 degrees F. Generously grease an 8x8 baking pan.

To make the topping: Combine the flour, oats, brown sugar and almonds in a large bowl until well-combined. Add in the pieces of butter and use your hands to squeeze and combine until the mixture becomes crumbly and resembles wet sand. (Alternatively, you can cut in the butter with a pastry cutter, or place all of the topping ingredients in a food processor and pulse until just blended. My favorite method is to use my hands, as I believe you get the best crumbly topping that way.)

Once finished, place topping in the fridge and begin making the apple filling.

To make the filling: Place butter and seeds from the vanilla bean in a medium saucepan, and turn heat on medium. After a couple of minutes the butter will begin to crackle and foam—make sure you whisk consistently during this process! Another minute or two, and you will notice the butter turning a slight brown (caramel) color on the bottom of the saucepan; continue to whisk and remove from heat as soon as the butter begins to give off a nutty aroma. Immediately transfer the butter to a bowl to prevent it from burning. Set aside to cool for a few minutes.

While the butter is cooling, place apples, 1/3 cup brown sugar, cinnamon and bourbon in a large bowl and toss to combine. Add the brown butter to this apple mixture and toss again to combine.

Take a heaping ½ cup of the topping mixture and toss with the apple mixture. Place the apple mixture in prepared pan and sprinkle evenly with topping. It may seem like a lot of topping, but the apples will cook down and the topping will provide an excellent crunchy exterior.

Bake the crisp on a baking sheet (just in case the filling bubbles over!) for 55-60 minutes, or until topping is golden brown and filling is bubbling. Remove from oven and cool 10 minutes on wire rack. Serve warm with vanilla bean ice cream.