Place the flour, salt, and sugar in a large bowl and mix with a fork.

In another bowl, whisk together the milk and eggs. When the texture is uniform, add the vanilla extract and 4 tablespoons of melted butter. Stir to combine.

Pour half of the milk mixture over the flour and stir to make a paste. Once incorporated, add the rest of the milk and stir to create a very thin batter.

Cover and refrigerate the batter for at least 30 minutes or up to 48 hours.

Heat a 10-inch nonstick skillet over medium heat. Brush the skillet with a thin layer of melted butter.

Pour about 2 ounces of batter (1/4 cup) into the pan. Swirl the pan until the batter has spread evenly into a round shape, using a spatula if necessary. Cook the crepe until just set, about 30 seconds. Do not let the edges brown. Flip and cook for another few seconds. Remove the crepe from the pan and repeat with the remaining batter.

Keep the crepes warm in a 200°F oven while you prepare the filling.

Mix the shredded cheeses in a small bowl and set aside.

Heat a large skillet over medium heat and add the olive oil. Season both sides of the chicken breasts with seasoned salt and place them in the skillet. Cook for 6 to 7 minutes per side or until cooked through. Remove the chicken breasts from the skillet and cut them into bite-sized pieces.

Place the onions in the skillet along with a pinch of salt, adding more oil if necessary. When the onions have become translucent, return the chicken to the skillet and add the spinach. Stir once or twice, and turn off the heat.

Place 1 tablespoon of shredded cheese and 1/4 cup of the chicken mixture in the center of each crepe. Roll up the crepes.

Place 2 filled crepes on each plate. Pour hollandaise sauce over the crepes and sprinkle with about 1 tablespoon of chopped tomatoes.