Bring a large pot of lightly salted water to a boil.

Cook orzo in the boiling water, stirring occasionally until cooked through but firm to the bite, about 11 minutes.

Drain orzo, reserving some of the water.

Combine spinach and beets in a blender, adding reserved water as needed to help the mixture blend smoothly.

Blend until smooth.

Melt butter in a large pot over medium heat.

Stir blended spinach mixture with the melted butter and cook until the color begins to change, 5 to 7 minutes.

Stir remaining water into the mixture to thin the liquid.

Stir drained orzo pasta into the soup.

Season with thyme, salt, and pepper to taste.

Remove pot from heat and stir sour cream through the soup.

Sprinkle with Cheddar cheese to serve.