I start by peeling and slicing my pears into pieces that aren't too thin, since they soften a lot in the oven. I toss them in a bowl with vanilla, cinnamon, nutmeg, and a pinch of salt until every slice is coated. If my pears feel especially juicy, I stir in a spoonful of flour to help thicken things up.
Once the pears are coated, I spread them evenly into a greased 8-inch square baking dish. A cast iron skillet works well too if that's what I have on hand. I try to keep the layer fairly even so everything bakes at the same pace.
In a separate bowl, I combine softened butter, flour, oats, both sugars, pecans, and a little salt using a fork or my fingers. I'm aiming for clumps rather than fine crumbs, since those little clusters bake up golden and crunchy. Then I scatter the mixture evenly over the pears.
I bake the crisp at 350°F for about 45 minutes, until the topping turns deep golden brown and the fruit is bubbling around the edges. Once it's done, I let it rest for five to ten minutes before serving so the filling has time to set slightly.