Preheat the oven to 400°F (200°C). Lightly grease a 9 x 13 baking dish. Set aside.
In a large skillet, heat olive oil over medium heat. Add ground beef and cook until browned. Drain excess fat if needed.
1 ½ pound lean ground beef, 1 tablespoon extra virgin olive oil
Add onion and garlic, cooking for 2 minutes until fragrant. Add the carrots and potatoes, cooking for another 3 minutes while stirring. You’ll notice some caramelization appearing - that is from the natural sugars from the vegetables and adds depth of flavor.
1 small yellow onion, 2 cloves garlic, 1 cup carrots, 1 cup potatoes
Stir in tomato paste, Worcestershire sauce, thyme, salt, and pepper.
2 tablespoons tomato paste, 1 tablespoon Worcestershire sauce, 1 teaspoon dried thyme, 1 teaspoon fine sea salt, ½ freshly ground black pepper
Sprinkle flour over the mixture, stirring to coat. Slowly pour in beef broth while stirring. Simmer for about 5 minutes until thickened. Stir in peas and remove from heat.
2 tablespoons all-purpose flour, 2 cups low sodium beef broth, 1 cup frozen peas
Transfer the filling to the prepared casserole dish. Set aside.