Position broiler rack 4” from heat source. Generously coat a 10” oven proof nonstick skillet with cooking spray.
In a large pot bring salted water to a boil, add potatoes and cook for approx.. 10 min. until fork tender. Add broccoli and peas for the last 5 minutes of cooking time. Drain and separate broccoli from the potatoes and peas.
In a large bowl whisk together, eggs, Dijon mustard, minced garlic, dried thyme, and pepper until well combined.
Gently stir in potato and peas using a spoon. Pour mixture into the prepared skillet; arrange broccoli spears on top.
Place skillet on cooktop and over medium heat, cook frittata until edges are just set about 10-12 min.
Heat broiler and broil pan until center is set and broccoli is lightly browned, approx. 10 min. If it looks like your broccoli is browning too much, remove pan from oven, lower rack, and put pan back into the oven. There should be no liquid on top. Test with a toothpick to ensure set all the way through.
Cut into wedges and serve.
Drizzle with EVOO if desired and if you want to spice it up, serve with your favorite hot sauce!