Preheat your oven to 350 degrees f. and lightly grease a pie dish with oil and set aside.
Roughly chop your spinach and scallions. I didn't chop my spinach because it was really small leaves, but if it was larger then it would need to be roughly chopped.
In a large mixing bowl, beat eggs together with mustard powder, and a good pinch of sea salt & pepper; until fluffy and well combined.
Gently fold in the milk, yogurt, spinach and scallions.
Pour your mixture into your prepared dish.
Crumble the bacon over top.
Sprinkle with shredded cheese and bake uncovered for 30-40 minutes, just until quiche is light golden and set in the center.
Serve hot or cold - it's great both ways!