Preheat oven to 350°F (175°C) and grease a 9x5-inch loaf pan with softened butter.
Heat olive oil in a medium skillet over medium-high heat. Add sausage and cook, breaking up with a spatula, until lightly browned, about 5 minutes.
Add celery and onion to the skillet; cook, stirring occasionally, until softened, about 7 minutes.
Stir in garlic and cook for 1 minute until fragrant.
Shake the stuffing mix to redistribute seasonings, then add it and water to the skillet. Gently stir until combined.
Fold in half of the shredded cheddar (3 oz) and 1 tablespoon parsley. Season with salt and pepper to taste. Remove from heat.
In a small bowl, blend softened butter with remaining 1 tablespoon parsley.
Carefully separate refrigerated biscuit dough into 16 halves. Spread parsley butter over each piece.
Top each buttered biscuit piece with 1 tablespoon shredded cheddar and about 2 tablespoons of the stuffing mixture, pressing lightly.
Stack 3 to 4 biscuit pieces together, pressing gently to adhere.
Arrange stacks on their sides in prepared loaf pan, fitting tightly. Tuck any loose filling between layers.
Dollop remaining parsley butter on top of the stacked bread.
Place loaf pan on a baking tray and bake for 45 to 50 minutes, until golden and cooked through.
Cool bread in pan on a wire rack for 5 minutes. Run a knife around the edges, then invert onto the wire rack.
Let cool 10 minutes before sprinkling with extra parsley and serving.