Preheat your oven to 400°F and line a tray with baking paper. Toss the pumpkin cubes with olive oil, salt, and pepper, then spread them out in a single layer. Roast for about 20 minutes, until the edges are golden and the pumpkin is fork-tender.
While the pumpkin roasts, shred your cooked chicken using two forks or your hands if it's cool enough to handle. If you're starting from raw chicken breast, poach or pan-fry it first, then shred once it's cooled slightly.
Heat a dry skillet over medium heat and warm each tortilla for about 20 seconds per side. This step keeps them soft and pliable, which makes rolling the wraps much easier without any tearing.
Lay a tortilla flat and spread a spoonful of yogurt down the center. Add a layer of roasted pumpkin, gently mashing it slightly with a fork, then top with shredded chicken, spinach, and crumbled feta.
Fold in the sides of the tortilla, then roll it up tightly from the bottom, tucking the filling in as you go. Sprinkle with toasted pepitas before serving, or slice in half for easier eating on the go.