Preheat oven to 350°F. In a small pot over medium high heat, melt butter. Cook for 5 to 8 minutes until it begins to turn golden brown, milk solids separate and rise to the top. Allow to cool slightly.
In a medium bowl combine oats, brown sugar, flour, and 1/2 teaspoon cinnamon. Use a wooden spoon to combine dry mixture and butter.
In a large bowl combine granulated sugar and 1/2 teaspoon cinnamon. Toss apple halves in mixture. Arrange apple halves cut side up in an 8x8 baking pan. Sprinkle the buttery oat mixture evenly on top. Place a few pieces of pecans on each.
Bake in the oven until the apples are tender, slightly firm, and the crisp topping is golden and crispy. The air should smell like caramelized sugar, apples, and butter.
Allow the apples too cool and serve while still warm with heavy cream.