While we know that all fruits and vegetables are good for us and our diets should focus heavily on produce, we may want to be more selective about which types we place on our plates. According to the Centers for Disease Control and Prevention, some fruits and vegetables promise more nutritional bang for their buck than others.

The United Nations and the Institute of Medicine studied various fruits and vegetables, calculating how many nutrients per calorie they provided, essentially trying to find which ones had the highest concentration of powerful nutrients. The rankings are based on the amount of 17 particular nutrients (vitamins A, B6, B12, C, D, E, K, potassium, fiber, protein, calcium, iron, thiamin, riboflavin, niacin, folate and zinc), considered to be most important for overall good health and the prevention of chronic diseases such as cancer and heart disease.

Among the top-ranked produce picks is spinach. Spinach is near the very top of the list, ranked as the 5th most nutritious food, with a nutrient density score of 86.43 (out of 100). It's chock-full of beneficial nutrients and flavor. But you may not know how to use it as the star of a meal. Not to worry, we've put together two amazingly delicious and simple recipes.

Black Bean & Spinach Quesadillas

Ingredients

1/4 can black beans, drained and rinsed
3 cups fresh spinach, chopped
1 medium onion, diced
1 bell pepper, diced
2 ounces reduced-fat pepper jack cheese, shredded
1/4 teaspoon cumin
1/4 teaspoon ground black pepper
Pinch ground cayenne pepper
1 teaspoon olive or canola oil
3 8-inch whole-wheat flour tortillas
Non-stick cooking spray

Directions

Heat oil in large skillet. Saute onion and bell pepper about five minutes. Add cayenne and cumin. Add spinach and cook about five more minutes.

Add beans and black pepper and stir until entire mixture is hot. Remove from heat, set aside.

Wipe skillet clean and spray with non-stick cooking spray.

Lay tortilla in skillet and spread a third of the veggie-bean mixture onto one half of the tortilla. Sprinkle about one tablespoon of shredded cheese onto mixture.

Fold tortilla in half and cook about four minutes on each side, until golden and crispy. Repeat until you have three completed quesadillas.

Cut into two wedges and serve garnished with fresh chopped cilantro, salsa, or fat-free Greek yogurt (in place of sour cream) if you desire.

Nutrition Facts (per 1 folded quesadilla): 238 calories, 6.7 grams fat, 433 milligrams sodium, 33.6 grams carbohydrates, 11.3 grams protein

Mini Egg White & Spinach Frittatas

Ingredients

1 cup vegetables of your choice (asparagus, mushrooms, broccoli, peppers, etc), chopped
1 medium onion, diced
2 cups fresh spinach, chopped
4 cloves garlic, minced
1 teaspoon olive or canola oil
2 cups egg whites
1 teaspoon dill, oregano, basil or thyme
Salt and ground black pepper to taste
4 ounces reduced-fat feta or cheddar cheese, shredded or crumbled
Non-stick cooking spray

Directions

Preheat oven to 350 degrees F. Spray muffin tin with non-stick cooking spray.

In a skillet, heat oil and saute garlic about 30 seconds, until fragrant. Add onion, saute until translucent. Add vegetables and saute another three to four minutes. Add spinach and cook until wilted. Remove from heat.

In a large bowl, whisk together egg whites, herbs, spices, and salt.

In a muffin tin coated with non-stick cooking spray, evenly layer vegetables and eggs, and top with cheese.

Bake about 30 minutes until mini frittatas spring back when you gently touch them.

Makes 12 individual portions, which can be frozen for about a month. With such a low calorie count, you could enjoy two to three mini frittatas per meal. Garnish with fresh herbs or top with a spicy salsa.

Nutrition Facts (per 1 mini frittata): 47 calories, 1.2 grams fat, 130 milligrams sodium, 2.2 grams carbohydrate, 7.2 grams protein