Step 1
Preheat the oven to 425°.
Step 2
Heat a medium nonstick ovenproof skillet (such as cast-iron) over medium-high. Add the butter. When it foams, add the spring onions and potato; season with salt and pepper. Cook, stirring occasionally, until the spring onions and potato are tender, about 5 minutes. Add the garlic to the skillet and cook, stirring often, until aromatic, about 2 minutes.
Step 3
In a large bowl, whisk the eggs, garam masala, and baking powder. Stir in the herbs; season with salt. Pour the eggs into the skillet and transfer to the oven. Bake until the eggs are just set in the center, 12 to 15 minutes. Cut into wedges.