Preheat the oven to 350 degrees F. In a metal bowl, whisk together milk, water, and sugar. Stir in yeast and 1 cup all-purpose flour; let stand in a warm place until bubbly, about 5 minutes. Stir in eggs, remaining 1 1/2 cups all-purpose flour, cake flour, 1 tablespoon salt, and cooked bacon. Using a stand mixer fitted with a dough hook, knead for 8 minutes. Work dough into a ball and let rise in a warm place until doubled in size, about 1 hour.
Pour 2 tablespoons olive oil onto a metal 9 by 13-inch baking dish. Transfer dough to baking dish and flatten with your fingers (make sure dough reaches edge of pan). Evenly scatter the roasted vegetables on top and gently press them into dough. Place in a warm spot and let rise again until doubled, about 20 minutes. Sprinkle with sea salt.
Bake until evenly golden and, when turned out of the pan, bottom is browned, 12 minutes. Let cool completely 5 minutes in pan; remove to a wire rack to cool completely. Cut into squares to serve.
At her shop, Dynamo Donuts in San Francisco, Sara Spearin always uses leftover dough from her famous bacon doughnut to make a pan of focaccia. It has become so popular that she created this recipe for people to make at home.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.