Add and shallots and mushrooms to the sausage. Cook until mushrooms are just tender, about five minutes. Remove from heat. Set aside.
While your sausages cooking, combine eggs and cream along with salt-and-pepper in a stand mixer. Beat on high for one minute or until your eggs are light and fluffy.
Add in your torn chard leaves to your egg mixture. Pour over the sausage mushrooms and shallot. Top with grated Swiss cheese.
Bake uncovered at 350° for 45 minutes or until lightly brown and crispy on top.
Remove from the oven and let stand for five minutes prior to serving.
Recipe by Millhorn Farmstead at https://millhornfarmstead.com/mushroom-swiss-and-sausage-frittata/