Fill a large pot with 1 to 1 and ½ inches water. Bring to a boil.
Place your steamer basket in the pot. Add the broccoli and cauliflower. If you don't have a basket, use a mesh strainer. If you don't have a mesh strainer, roll up 3 balls of aluminum foil and put them in the pot. Then place a heat-safe plate on top of them. Alternatively, see notes for microwave or boiling directions.
Cover and cook the broccoli and cauliflower alone for 2 minutes.
Add the frozen mixed veggies to the steamer basket. Gently stir to promote even cooking. Cover and cook for 4 to 5 more minutes.
Turn off the heat and carefully remove the steamer basket from the pot. Transfer the veggies to a mixing bowl.
Warm the butter in a butter warmer or saucepan over medium-low heat until melted. You can also melt it in the microwave. Stir in the garlic salt, thyme, and pepper.
Pour the butter and seasonings over the cooked vegetables in the mixing bowl. Stir until coated. Serve immediately.
Leave a rating or review by tapping the stars on this recipe card (above) or in the comments section (at the end of the post).
Notes
If you don't have a steamer, bring a couple cups of water to a boil. Add the veggies, cover, and reduce heat to maintain a gentle boil. Cook for 5 to 7 minutes or until tender. You can also microwave them with 1 cup water in a microwave-safe bowl covered with a plate for 4 to 5 minutes.
Feel free to substitute fresh or other frozen vegetables, but keep in mind that cooking time may vary depending on the type and size of vegetable.
Other seasoning ideas to mix with melted butter include fresh garlic and parmesan cheese; lemon juice, garlic, and dill; Italian seasonings like parsley, oregano, and basil; cumin and lime juice
Store leftovers in an airtight container in the fridge for 2 to 3 days. Reheat in the microwave or in a skillet until warmed through.