Dice the stems of the swiss chard and chop up the leaves. Slice zucchini or use a spiralizer to get zucchini noodles.
Add swiss chard and zucchini to the pan with the other vegetables and toss for 1 minute.
Whisk together eggs, milk, garlic powder, and salt and pour over the vegetables. Tuck veggies down into the egg mixture if necessary. Turn the heat up to medium and allow the frittata to cook for 3-4 minutes until the bottom sets.
Turn off the heat and top the frittata with a sliced tomato and cracked pepper. Use an oven mitt to transfer the cast iron pan into the oven. Bake for 15-18 minutes, until a knife in the center comes out clean and the edges are browning.
Slice and serve.
Recipe by Uproot Kitchen at https://uprootkitchen.com/2015/09/11/zucchini-noodle-frittata-with-swiss-chard/