• Preheat oven to 350 degrees Fahrenheit.

Make the crumble topping:

• In a large bowl, combine the brown sugar, oats, all-purpose flour, kosher salt, crushed pecans, cinnamon, and butter.
• Use your hands to work the butter into the dry ingredients until it forms a crumble.

For the filling:

• In a large nonstick skillet over medium-high heat, melt the butter. Add the brown sugar and stir to combine.
• Add the sliced peaches and cook for 2 more minutes, stirring occasionally.
• Add the lemon juice, half and half, and peach preserves. Cook for 4 minutes to reduce the liquid a bit, stirring occasionally.

Assemble and bake:

• Pour the peach mixture into an 8x8-inch glass baking dish. Top evenly with the crumble topping. You can use as much or little as you like and freeze the rest. I used ¾ of the topping.
• Bake for 40 minutes or until the edges are bubbling and the top is golden brown.