Preheat your oven to 350°F (175°C). Grease a baking dish with olive oil to prevent sticking. This step ensures easy serving and avoids any burnt edges that might stick to the dish.

In a saucepan over medium heat, melt the butter. Continue cooking until it turns a deep amber color and emits a nutty aroma. This process enhances the flavor profile of the crumble.

In a large bowl, mix the sliced pears thoroughly with granulated sugar, vanilla extract, and ground cinnamon. Stir until the sugar dissolves slightly, and the pears are evenly coated. The mixture should be fragrant, with the cinnamon and vanilla enhancing the natural aroma of the pears.

Carefully transfer the pear mixture into the prepared baking dish, ensuring it is spread evenly across the bottom. This step is crucial for achieving uniform cooking and even flavor distribution. Make sure the pears are not piled up, as this allows for proper heat circulation and prevents uneven baking.

In a separate bowl, combine the flour, oats, chopped nuts, salt, and brown sugar. Gradually incorporate the browned butter, mixing until the texture becomes crumbly and resembles coarse sand. Ensure the mixture is evenly coated with butter, creating a uniform consistency without any large clumps remaining.

Evenly sprinkle the crumble topping over the pears, covering them completely. This layer will bake into a golden, crunchy topping that contrasts with the soft pears.

Place the dish in the preheated oven set to 350°F (175°C) and bake for 35-40 minutes. The crumble is done when the topping turns a rich golden brown and the pears are soft and easily pierced with a fork. Check for bubbling juices around the edges.

About 20 minutes into baking, inspect the crumble. If the topping appears to be browning excessively, tent it with foil. This will help prevent burning while ensuring the pears continue to soften and release their juices, achieving a tender texture.

After baking, take the crumble out of the oven and place it on a wire rack. Allow it to cool for approximately 10 minutes. This cooling time helps the juices redistribute, ensuring that the crumble holds together better when you serve it.

Serve the crumble warm, optionally with a scoop of vanilla ice cream or a dollop of whipped cream. The contrast between the warm crumble and cold cream enhances the dessert experience.