In a large skillet, heat the oil over medium-low heat. Add the shallots and garlic and cook, stirring, until golden, 4 to 5 minutes.
Add the butternut squash, cranberries, maple syrup, and 1 tablespoon water. Cover, reduce the heat to low, and cook until tender, about 8 minutes.
Remove the pan from the heat and stir in the pear, spinach, pecans, sage, 1/4 teaspoon of salt, and pepper to taste.
Cut a slit into the sides of the tenderloins, being careful not to cut all the way through.
Season the inside and outside of the tenderloins with the remaining 1 1/4 teaspoons salt and pepper to taste.
Stuff each turkey breast with about 1 cup of the squash mixture. Tie each tenderloin closed with 4 pieces of kitchen string, cutting off the extra string.
Wipe the skillet clean and set it over medium-high heat. Spray with oil and carefully sear each turkey breast until browned, 2 to 3 minutes per side. Transfer to a slow cooker.
Cover and cook on low for 4 hours, or until the turkey is tender and the gravy is thickened.
