To prepare the butternut squash, heat the oven to 450°F. Peel and dice the squash into small 1/2-inch cubes. Toss the cubes with a drizzle of olive oil and salt. Spread on a baking sheet in a single layer so the cubes aren't too crowded (roast in two batches of necessary). Roast the cubes for 30 minutes, stirring halfway through, until soft. Set the cubes aside until needed.
Dice the bacon. Warm a skillet over medium-high heat and fry the bacon until cooked through, but not totally crispy. It will cook a little more in the oven. Set aside to drain on a paper towel.
Wash the kale. Spin it in a salad spinner or pat with a clean kitchen towel to get the kale as dry as you possibly can. Strip the leaves from the stems and tear into small 1/2-inch pieces. The stems can be saved for another purpose. Toss the kale with a little olive oil; if preparing the kale ahead of time, wait until just before assembling the pizza to toss with oil.
Slice the mozzarella into thin rounds.
Heat the oven to 500°F or as hot as it will go. If you have a baking stone, place this in the lower half of the oven while the oven warms.
To assemble and bake the pizzas, divide the dough into two halves and shape each into 10-inch rounds. Working one round at a time, brush with olive oil and sprinkle lightly with salt. Lay half the rounds of mozzarella on the pizza and arrange 1/2 cup of the roasted squash and half the bacon across the dough. Scatter half of the kale over top. (Note: You may have more squash than needed for this recipe; save the rest for another meal.)
Transfer the pizza to the oven. Bake for 7-10 minutes, until the kale is crispy and the crust is dark golden. Assemble and bake the second pizza as the first. Let the pizzas cool slightly before slicing and serving.