Place bacon into a skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes.
Drain the bacon on a paper towel-lined plate, allow to cool, and crumble the bacon.
Preheat the oven's broiler and set the oven rack about 6 inches from the heat source.
Whisk eggs and milk in a bowl until smooth.
Heat vegetable oil in an omelet pan or skillet over medium heat and pour in egg mixture. Swirl the pan to coat the bottom of the skillet evenly with the eggs. Cook until the omelet is barely set but the edges are not hard, 1 to 2 minutes.
Gently flip the omelet over and cook the other side, about 1 more minute.
Place omelet onto a broiler-safe baking sheet; top the omelet with crumbled bacon, diced tomato, deli turkey, and Monterey Jack cheese.
Fold the omelet in half to enclose the fillings and place the omelet under the broiler until the cheese bubbles, about 2 minutes.
Place omelet onto a serving platter and arrange the tomato slices on the omelet.
Pour hollandaise sauce over the omelet and sprinkle with parsley flakes to serve.
