Pesto Spaghetti Squash Bake

Preheat oven to 475 degrees F. Cut squash in half lengthwise; scoop out and discard seeds and loose pulp. Place the halves, cut-side down, on a parchment-paper-lined baking sheet. Bake until the flesh yields slightly when pressed, 25 to 30 minutes. Transfer the squash halves, cut-side up, to a plate; let stand until cool enough to handle, 10 to 15 minutes.

Meanwhile, reduce oven temperature to 375 degrees F. Heat a large skillet over medium-high heat. Add oil and spinach; cook, stirring often, until the spinach is wilted and some of the liquid has evaporated, 3 to 4 minutes. Add artichokes and stir to combine. Add pesto and flour; stir until well combined. Cook, stirring, for 1 minute; remove from heat.

Cut each squash half in half crosswise, creating 8 pieces. Using a fork, gently scoop out squash strands from the shells (about 3 1/2 cups total), leaving a small amount of squash in each shell to retain its shape. Place the scooped squash strands in a fine-mesh strainer over a medium bowl. Gently press to remove excess liquid; discard liquid. Add the squash strands, Parmesan and salt to the mixture in the pan and stir gently to combine.

Place the squash shells on the baking sheet. Spoon about 1 cup squash mixture into each shell. Divide mozzarella pieces among the tops and sprinkle with panko; lightly coat the panko with cooking spray. Bake until the cheese is bubbly and melted and the panko is lightly browned, 10 to 15 minutes. Serve hot.