Preheat the oven to 375°F; lightly coat a baking sheet with a few spritzes of olive oil.
In a medium-size skillet, heat the broth over medium heat.
Saute the onions, peppers, and seasoning in the broth for about 5 minutes, or until the veggies are tender and being to brown.
Stir in the spinach; cook just until the spinach wilts, about 1 minute.
Remove the veggies from the heat; stir in the egg white and chia seeds.
Mound the spinach filling mixture into the mushroom caps.
Sprinkle the mushroom caps with equal portions of the goat cheese.
Bake for 15 minutes, or until the mushrooms are heated through and the cheese is melted.