Preheat oven to 400 degrees Fahrenheit. Line a baking sheet with parchment paper.
In a medium bowl, mix together instant oatmeal, baking powder, and salt.
In a small bowl, whisk together egg, honey, oil, and water.
Add egg mixture to bowl with oat mixture and incorporate well. Using your hands, make into a ball and place on parchment paper. Press down on oat mixture and form into rectangle, it should be roughly 11-inch by 5-inch.
Place in oven and bake for 8 minutes.
While oat flatbread is cooking, prepare the toppings.
For the Savory Flatbread: Once out of the oven, spread pesto or pizza sauce on the oat flatbread then top with mozzarella and tomatoes. Return to oven for 10 minutes then broil for 1 to 2 minutes till golden brown. Garnish with basil.
Slice into pieces and serve.