In a large bowl, combine the softened butter, granulated sugar, and vanilla extract. Add the flour, salt, oats, and chopped pecans, and combine. Shape the dough into a log, wrap it with plastic wrap, and freeze for 1-2 hours.
Preheat the oven to 350°F.
Add the peeled and sliced nectarines, brown sugar, cinnamon, and salt in a bowl and toss to combine.
Pour the nectarine mixture into a quiche, pie dish, or square baker.
Remove the dough from the freezer and cut it into slices about ¼ inch thick. Layer the slices of dough on top of the nectarines. They can overlap in places. I like to leave a little bit of space on the top so that when fully baked, some of the nectarines are still visible from the top.
Place the dish on top of a baking sheet to catch any potential overflow and bake at 350°F for 1 hour. The top should be a medium golden brown color throughout when done.
Notes
Choose Firm Nectarines: This helps make it easier when peeling the nectarines, and it prevents the filling from being too mushy. If your nectarines are more ripe, consider leaving the skin on, as they are harder to peel when they are softer.
Oats and Pecans: I love to add these to the topping for flavor and texture, but they can just as easily be left out without making any other adjustments to the recipe.
Freeze the Dough: Freeze the dough for the topping. This ensures that it has a nice thin, crispy top when baked.
Layering the Dough: I like to leave a few gaps in the topping (it will spread as it bakes) so that the golden color of the nectarines is a little bit visible when fully baked.