Add chicken tenders and buttermilk in a bowl and let rest (at least 30 minutes, up to 8 hours) in refrigerator.
In a large saute pan over medium high heat, add bacon and cook until crispy. Remove to paper towel covered plate. Reserve all grease in the pan.
Add flour, baking powder, salt, pepper, garlic and paprika to a bowl and stir to combine.
Add enough oil to the bacon grease to be one inch deep. Once hot (around 350degF), begin frying chicken. Remove each piece of chicken from buttermilk and put right into flour mixture. Fully coat with flour and place right into hot oil. Cook for 4 minutes on each side and remove to a baking rack over a paper towel covered baking sheet. Repeat with remaining chicken tenderloins.
Once all chicken is cooked and slightly cooled, cut each tenderloin into 3-4 pieces (about 1-inch chunks). Start to build the tacos with a sprinkle of lettuce, and cheese. Tops with 4-6 pieces of chicken then drizzle with ranch dressing. Then sprinkle with cooked bacon and crispy fried onions.