Step 1

Place racks in middle and lower third of oven and set a rimmed baking sheet on each; preheat oven to 450°. Toss squash with oil in a large bowl; season with salt and pepper. Remove baking sheets from oven and divide squash between them, arranging in a single layer. Roast, rotating sheets halfway through, until browned and tender, 15–25 minutes. Set squash aside; reduce oven temperature to 350°.

Step 2

Do Ahead: Squash can be roasted 1 day ahead. Let cool, then transfer to an airtight container. Cover and chill. Bring to room temperature or heat slightly in a microwave before using.

Step 3

Toss pecans with 1 tsp. oil in a small bowl; season with salt. Toast on a rimmed baking sheet, tossing halfway through, until slightly darkened and fragrant, 8–10 minutes. Let cool, then coarsely chop. Set ½ cup pecans aside for serving.

Step 4

Blend shallot, orange juice, mustard, maple syrup, ¼ cup lemon juice, and remaining pecans in a blender until mostly smooth. With motor running, gradually stream in ½ cup oil and blend until emulsified and smooth. Season dressing with salt and pepper.

Step 5

Toss radicchio and half of dressing in a large bowl to coat; season with salt and pepper. Arrange on a platter. Toss reserved squash with remaining dressing in the same bowl to coat; season with salt and pepper. Arrange over radicchio.

Step 6

Toss Asian pear with 1 Tbsp. lemon juice in a small bowl. Top salad with Asian pear, cheese, parsley, and reserved pecans. Squeeze juice from lemon half over and drizzle with oil; season with more salt and pepper.

Step 7

Do Ahead: Vinaigrette can be made 1 day ahead. Cover and chill. Bring to room temperature before using.