In a large pot over medium heat, add a splash of olive oil and sauté the diced onion (if using) and minced garlic until fragrant and onion is translucent, about 3-4 minutes.

Stir in the orzo, pour in the vegetable broth and mix well. Bring to a gentle boil, then reduce to a simmer. Cook for about 10-15 minutes until the orzo is tender and broth is mostly absorbed.

Once the orzo is tender, fold in the broccoli florets and heavy cream. Stir to combine and cook for an additional 3-5 minutes until broccoli is bright and tender.

Remove from heat and stir in the shredded cheddar cheese until melted and blended smoothly.

Taste and adjust seasoning with salt and pepper as preferred, then let sit for a moment before serving.