Step 1
Preheat the oven to 425 degrees F (220 degrees C).
Step 2
Form sausage into mini meatballs and place on a rimmed baking sheet.
Step 3
Bake in the preheated oven until nicely browned 15 to 18 minutes. Transfer sausage to a paper towel-lined plate.
Step 4
Reduce oven temperature to 350 degrees F (175 degrees C). Grease a deep-dish pie pan or a 2-quart casserole dish.
Step 5
Combine boiling water and soup base in a bowl to create a double-strength chicken stock. Set aside.
Step 6
Melt butter in a skillet over medium heat; stir in onion. Cook and stir until the onion has softened and turned translucent about 5 minutes. Add mushrooms and bell pepper. Cook stirring occasionally until mushrooms begin to soften 5 to 8 minutes. Add garlic; cook and stir until fragrant about 1 minute.
Step 7
Sprinkle 1/4 cup flour over the vegetables and stir until all are coated. Cook and stir for 2 minutes. Add reserved chicken stock and cream. Cook and stir until thickened about 5 minutes. Stir in sausage spinach and cooked chicken. Pour mixture into the prepared pan.
Step 8
Combine remaining flour celery seed paprika and salt in a medium mixing bowl. Cut in shortening with a pastry knife or fork until mixture looks like coarse meal. Sprinkle ice water over flour mixture and stir unto a ball.
Step 9
Transfer dough onto a lightly floured surface. Flour a rolling pin and roll dough into a circle large enough to cover the prepared pie pan or casserole dish. Carefully place dough on top of chicken filling and make several slits in the top.
Step 9
Bake in the center of the preheated oven until filling is bubbly and crust is golden brown 40 to 45 minutes. Cook on a rack for 10 minutes before serving.