Heat the olive oil in a Dutch oven over medium heat.
Add onion, garlic, rosemary and thyme; sauté until fragrant, about 5 minutes.
Sprinkle beef with salt and pepper. Raise heat to medium-high and add beef; brown on all sides.
Add beef broth and whisk up all of the browned bits from the bottom of the pan.
Add calabaza squash and stir to combine well. Bring mixture to a boil then reduce heat, cover and simmer for 1 hour until beef is cooked and fork-tender.