Preheat your oven to 425 degrees F and place the oven rack towards the top of your oven.
On a rimmed baking sheet / sheet pan, drizzle 2 tablespoons of the melted butter.
Add the zucchini and summer squash to the pan, and toss to coat in the melted butter. Move it to the sides of the pan, so there is a space in the center.
Place the salmon filet skin-side down in the center of the pan.
Season the top of the salmon and the zucchini and summer squash with a generous amount of salt and pepper.
Mix the remaining two tablespoons of butter with the minced clove of garlic, the 2 tablespoons of chopped fresh parsley, and the juice from one lemon (about 2 tablespoons).
Pour the melted butter mixture over the salmon evenly. You can spread it around with your hands or, alternatively, use a brush to brush the butter mixture on.
Bake at 425 degrees F for 20 minutes, or until salmon is fully cooked (you can check by flaking it apart with a fork- if it flakes easily, it's done).
Serve garnished with extra parsley and with extra lemon slices or wedges, if desired. Make sure to get all the garlic butter yumminess from the bottom of the pan when serving!
Optional: broil at the end to brown the salmon and veggies. Broil for the last 5 minutes of cooking. Make sure to keep a close eye on it so it doesn't burn!
Other veggies may be substituted for the zucchini and summer squash, but they should be quick-cooking vegetables. For example, cherry tomatoes, asparagus, thinly sliced carrots, and small broccoli florets would work well. White and sweet potatoes, thick-cut carrots, butternut squash, and similar veggies will take too long to cook, and would have to be roasted for some time before adding the salmon to the pan.
For a paleo or dairy-free version, use ghee or olive oil instead of butter.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.