Preheat the oven to 325°F (163°C). Line the bottom and sides of an 8-inch or 9-inch baking pan with aluminum foil or parchment paper, leaving enough overhang on all sides. Set aside.

Mix the cookie crumbs, sugar, and butter together in a medium bowl until combined. Press into the bottom of the prepared pan. The crust will be thick. Bake the crust for 10 minutes as you prepare the filling.

Turn oven up to 350°F (177°C).

Using a handheld or stand mixer fitted with a paddle attachment, beat the cream cheese and sugar together in a large bowl on high speed until creamy and smooth, about 1 minute. On low speed, add the eggs one at a time, beating well after each addition. On medium speed, beat the vanilla, pumpkin, yogurt, cinnamon, cloves, nutmeg, and ginger in. Continue beating until everything is combined and creamy. Pour the filing into the warm crust. Set aside.

Whisk the oats, brown sugar, cinnamon, and flour together in a medium bowl. Cut in the chilled butter with a pastry blender or two forks (or even with your hands) until the mixture resembles coarse crumbs. Sprinkle evenly over filling.

Bake for about 45 minutes, making sure to loosely cover the bars with aluminum foil around the 30 minute mark. The foil prevents the top from getting too brown. The bars are done when the edges are lightly browned and the center is set—this could be slightly before or after the 40 minute mark.

Allow to cool in the pan set on a wire rack at room temperature for 1 hour. Transfer to the refrigerator to chill for 3 additional hours or overnight. Lift the foil or parchment out of the pan using the overhang on the sides and cut into bars. I usually cut them into 16 smaller bars, but you can cut them into 12 larger bars.

Drizzle bars with icing or top with whipped cream if desired.