Place the chopped bacon in a cold skillet. Turn heat to medium and cook until crispy and fat has rendered. Remove bacon bits to a paper towel, leaving about 2 tablespoons of fat in the pan.
Increase heat to medium-high. Add diced onion and cook for 2 minutes until translucent.
Add garlic and the thawed peas and carrots. Stir-fry for another minute until fragrant.
Toss in the cold rice. Break up any clumps with your spatula. Let the rice sit for 1-2 minutes without stirring to crisp up the bottom, then stir.
Push the rice mixture to the sides of the pan to create a well in the center. Pour in the whisked eggs.
Scramble the eggs in the center until softly set, then mix them into the rest of the rice.
Stir in the cooked bacon bits, soy sauce, sesame oil, and butter. Toss until everything is evenly coated and hot.
Garnish with sliced green onions and serve immediately.
