In a large skillet, sauté the leeks, onions, and garlic in canola oil over medium heat until lightly caramelized. Cool.
Meanwhile, heat the beef broth and butter in the microwave until warm (not hot).
In a large bowl, whisk together the flour, yeast, dried thyme, sugar, salt, and pepper.
Add the warm beef broth to the flour mixture in the stand mixer and use a dough hook until the dough forms a ball (approximately 5 minutes). (OR use a wooden spoon and some elbow grease to stir, and then hand-knead the dough on a lightly floured surface until a soft dough ball forms).
Add the cooled caramelized leeks and onion mixture to the focaccia dough and knead the mixture into the dough until fully incorporated.
Place the dough into a bowl that's been sprayed with olive oil spray. Also lightly spray the top of the dough. Cover the bowl with plastic wrap and allow the dough to proof (rise) for 60 minutes (in a warm draft-free place) or until doubled in size.
Once doubled, deflate the dough and then divide into three equal portions.
Drizzle olive oil in the bottom of three 9" cake pans and sprinkle each with cornmeal.
Press each of the focaccia doughs evenly into the bottom of the prepared pans.
Cover the pans lightly with plastic wrap and allow the dough to proof again for 50-60 minutes in a warm, draft-free place.
Preheat the oven to 375-degrees (Fahrenheit) and bake the focaccia for 30-35 minutes or until lightly golden brown.
If desired, remove the focaccia from the oven and top with the honey mustard mayo sauce, chopped ham, and shredded mozzarella cheese.
Return the focaccia to the oven and continue to bake until the cheese has melted and turned golden in color.
Allow the focaccia to sit for 10 minutes before slicing and serving.