In a large bowl combine flour with salt, and pepper. Cut in the butter with a fork or pastry blender until the mixture looks crumbly.
In another bowl combine eggs, milk, and sweet potato puree. Add to the flour mixture and stir gently until combined. Don't overmix!
Divide dough into quarters. On a lightly floured surface roll each piece into a circle about 1/8-inch thick. Cut the circles to fit the size of the serving bowls. Brush with egg wash and bake on a parchment lined baking sheet until lightly golden brown. Remove from the oven and set aside.
For the filling:
Melt the butter in a medium saucepan over high heat. Add the onions and cook until soft. Add the garlic and cook for 1 minute. Stir in the flour and cook until deep golden brown. Slowly whisk in the hot milk and cook until thickened. Reduce the heat and cook for 5 minutes, whisking occasionally. If the mixture is too thick, thin with a little extra milk.
Add the mushrooms, turnips, carrots, onions, peas and chicken to the sauce and gently fold to combine and heat through. Season the sauce with salt and pepper and stir in the parsley.
Spoon the hot filling into bowls and top with a circle of the baked sweet potato dough.