Add chicken, chicken broth, cream cheese, chopped jalapeños, garlic powder, salt, cumin and chopped cilantro (if using) to slow cooker. Cover and cook on low for 6-8 hours or on high 3-4 hours.
Shred chicken, then return to the slow cooker with the liquid and stir to mix well.
Preheat the oven to 425°F and line a rimmed baking sheet with parchment paper and lightly spray with cooking spray.
Heat tortillas in the microwave for a few seconds to soften them up (this makes them easier to roll).
Place about 2 ½ - 3 Tbsp of the chicken filling in a line on one tortilla. Top with a sprinkle of Monterey jack cheese and a couple of jalapeño slices (if using). Starting with the bottom edge, roll the tortilla up towards the top, rolling it up into a cigar-like log shape.
Place taquito on prepared baking sheet and repeat with remaining tortillas, filling, and cheese. Lightly spray with cooking spray.
Bake for 12-14 minutes until cheese is melted and tortillas begin to brown.
If you'd prefer a crispier taquito, broil them for a couple of minutes, just be careful not to let them burn.
While the taquitos are baking, add avocado, cilantro, lime juice, and ranch dressing to a food processor or blender and blend until smooth.
Serve garnished with minced cilantro, diced avocado and avocado cilantro ranch dressing if desired.
