Flawed recipe

Asparagus Chicken

1/4 tsp Black pepper 1/2 tspRosemary 1/2 tsp Garlic Salt 2TB butter or margarine

1. Mix dry ingredients together in a mortar and pestle and grind to a powder
2. Put 2Tb butter in a bowl, dump in dried ingredients and whip together with a fork.

2 half pound chicken breasts about 10 Asparagus stalks(From produce or market) Aluminum foil 8x8 to 9x9 glass baking dish

Preheat oven to 375 farenheit

1. Slice a pocket horizontally along the top on the top of each chicken breast.
   A. Place ea chicken on its own foil, fold up sides and place in baking dish.
2. Slice approx 10 asparagus stalks perpendicularly into fourths and roll each piece in prepared butter
3. Put buttered asparagus pieces into sliced pocket on chicken
4. Brush excess butter on top of chicken breasts
5. Close up top of foil tightly into a loose shell.
6. Bake for 36 minutes

And it comes out over half raw. Why? I've baked chicken in a glass dish st that time and temp before, but never in a loose foil shell, which I did to keep the buttery goodness from the evaporating. Sort of a butter sauna. Do I need to adjust time or temp? If so, to what?