- Add the milk, eggs, mustard, thyme, and romano cheese to a medium sized mixing bowl. Using a hand mixer, whisk together on low speed until evenly combined & frothy. 
- To a large mixing bowl add the flour, baking powder, salt, and pepper. Using a fork, whisk them together until evenly combined. Set aside.  
- Add the zucchini & corn to the bowl, gently tossing to until evenly mixed. 
- Reserve a few tomato pieces, for topping the muffins, and add the rest to the mixing bowl. Stir gently to evenly combine and coat in the flour mixture. 
- Pour the wet mixture into the bowl of combined dry ingredients. Using a spatula, stir just until combined. Fold in a 1/2 cup of the feta cheese, but don't overmix. 
- Generously spray a muffin tin with non stick cooking spray to coat the wells. Spoon the batter in the prepared pan. 
- Top each with a couple pieces of tomato and feta, then bake the muffins at 400° for 20-22 minutes, or until all the muffins are puffed up and golden brown on top. 
- Remove the muffins from the oven, and allow them to rest for a full 5 minutes. 
- Run a butter knife around the edges of each to release them from the pan and then transfer them to a wire rack to finish cooling. 
- Serve the muffins as is, or with softened butter, and enjoy!