Bring a medium pot of salted water to a boil. Add the orzo and cook according to package directions until al dente, about 8-10 minutes. Drain and rinse under cold water to stop cooking. Spread on a sheet pan or plate to cool completely.

In a small bowl or jar, whisk together the olive oil, lemon juice, minced garlic, oregano, Dijon mustard, salt, and pepper until well combined. Taste and adjust seasoning as needed.

While the orzo cools, halve the cherry tomatoes, dice the cucumber, halve the olives, and thinly slice the red onion. Crumble the feta cheese.

Divide the dressing evenly among four wide-mouth quart-sized mason jars (about 2 tablespoons per jar). Layer in this order: chickpeas, olives, red onion, cooled orzo, cucumber, cherry tomatoes, feta cheese, and finally baby spinach on top.

Secure the lids tightly on each jar. Store upright in the refrigerator for up to 4 days.

When ready to eat, shake the jar vigorously to distribute the dressing throughout all the layers. Enjoy directly from the jar or pour into a bowl.