Preheat the oven to 350°F (177°C). Line a 12-cup muffin tin with liners or grease the cups thoroughly and set aside.

Heat a large skillet over medium-high and cook the breakfast sausage, breaking it into small pieces, until fully browned and no pink remains. Transfer the cooked sausage to a paper towel-lined plate to drain and allow to cool for about 10 minutes.

In a mixing bowl combine the lightly beaten eggs, shredded cheddar, sliced green onions, drained sausage, and Bisquick. Stir until the mixture is evenly incorporated.

Spoon the batter into the prepared muffin cups, filling each about three-quarters full to allow room for rising.

Bake in the preheated oven until the tops are golden and a toothpick inserted into the center comes out clean, about 20 minutes.

Remove the muffins from the oven and let them cool briefly in the pan for a few minutes before transferring to a wire rack. Serve warm or refrigerate for later.