Barbecued Chicken Sandwiches

3 to 4 boneless chicken breasts, cut in half lengthwise

1 onion cut into fourths

1 1/2 cups ketchup

1/2 cup barbecue sauce

1/4 cup brown sugar

1/4 cup pineapple juice

1 tablespoon Worcestershire sauce

3 tablespoons vinegar

Tabasco sauce to taste

1 teaspoon garlic powder

Salt and pepper to taste

Spray inside of crock pot with cooking spray. Add chicken breasts and onion. Mix sauce ingredients and pour over chicken. Cook chicken on high for 1 hour. Turn to low setting and cook an additional 2 to 3 hours. Remove chicken from crock pot and shred with two forks. Return to crock pot and set on warm. Serve on heated or grilled buns with coleslaw or guacamole.