FOR THE CHICKEN: bring a large pot of water to a boil. Carefully add chicken breasts to the pot and return to a boil. Cover with a fitted lid and remove from heat. Allow the chicken breasts to sit for approximately 25-30 minutes, or until fully cooked. Once cooked, remove chicken from the pot (the leftover water makes great chicken stock!) and set aside to cool.
FOR THE CAULIFLOWER: preheat oven to 400 degrees F and line a large baking sheet with parchment paper. In a large bowl toss together the cauliflower florets with 1 tablespoon of olive oil and a pinch of salt and pepper. Spread cauliflower onto prepared baking sheet and roast from approximately 20-25 minutes, or until cauliflower is cooked and browning at the tips. Remove baking sheet from the oven and set aside to cool.
In a medium mixing bowl, mix together the Greek yogurt, Buffalo wing sauce, garlic powder, shredded jalapeño jack cheese and chopped green onion. Set aside.
Once cool enough, shred the chicken breasts (using two forks or your fingers) and chop the cauliflower into small bits. Transfer both the chicken and the cauliflower to a large mixing bowl. To the same bowl mix in the yogurt wing sauce mixture until fully combined.
Preheat oven to 400 degrees F and line a large baking sheet with parchment paper. Assemble the taquitos by laying each tortilla on a flat, clean surface. Scoop approximately 1/4 - 1/3 cup of the buffalo chicken mixture into the center of each tortilla. Using your hands, tightly roll the tortilla. Transfer to the baking sheet and repeat until all of the buffalo chicken mixture has been used. Use a pastry brush to brush a thin layer of olive oil over the tops of each rolled tortilla and place them in the oven to bake for approximately 10-15 minutes, or until tortillas are just starting to brown at the edges and cheese has melted.
Remove from the oven and serve warm with a side of blue cheese or ranch dressing. Delicious served immediately and eaten leftover.