Chicken sausage, pesto, tomatoes and mozzarella combine to add Italian flavor to these frittata-like slices. Serve them for breakfast as is or in a sandwich (they're great for meal prepping).
To make ahead: Wrap individual slices in plastic wrap or layer between parchment paper in a sealed container. Refrigerate for up to 3 days or freeze for up to 3 months. To reheat, remove plastic, wrap in a paper towel and microwave on High for 30 to 60 seconds.