Grease a 13" x 9" pan with cooking spray, then line pan with parchment. In the large bowl of a stand mixer fitted with the paddle attachment, beat butter, granulated sugar, brown sugar, and vanilla on high speed until smooth and creamy, about 4 minutes.

Gently crush oats to break them down into some tinier pieces. Slowly add oats, flour, cinnamon, and salt and beat on medium-low speed until blended, 1 to 2 minutes.

Press base into bottom of prepared pan. Cover and refrigerate at least 20 minutes or up to 1 day.

Preheat oven to 350°. Bake base until beginning to firm up, about 10 minutes.

In a large bowl, whisk eggs, honey, granulated sugar, brown sugar, and vanilla until well combined.

Add pumpkin puree, cream, pumpkin pie spice, nutmeg, and salt and stir with a wooden spoon until combined.

Wipe out stand mixer bowl and paddle attachment. In stand mixer, beat brown sugar and butter on medium speed until well combined. Using your fingers, break down most of the oats as you add so you have some smaller pieces. Add flour and salt and beat on low speed until just combined.

Pour pumpkin filling over base in pan. Cover with foil. Cut a large slit lengthwise down center of foil.

Bake bars until pie filling is starting to set, about 50 minutes.

Uncover pan. Using your fingers, crumble oat topping over top, leaving some filling exposed. Continue to bake until crumble layer crisps up, about 15 minutes more.

Let cool at least 30 minutes (or ideally refrigerate up to 1 day) before cutting into bars.