Preheat your oven to 400°F and line a baking sheet with parchment paper for easy cleanup.
Toss the diced Yukon gold potatoes with olive oil, dried rosemary, and a portion of the sea salt and black pepper until evenly coated.
Spread the potatoes in a single layer on the baking sheet and roast for 20-25 minutes until they are golden brown and crispy.
In a small bowl, combine the ground turkey with dried sage and garlic powder, then form into a wide, flat patty slightly larger than the muffin.
Heat a non-stick skillet over medium-high heat and cook the turkey patty for 4-5 minutes per side until fully cooked through.
Whisk the large egg and egg whites together, then pour into a silicone egg ring or a small greased ramekin to cook until set and fluffy.
Split and toast the whole wheat English muffin until the edges are slightly charred and warm.
Assemble the sandwich by placing the turkey sausage patty on the bottom half of the muffin, followed by the egg round, and the top muffin half.
Serve the warm breakfast sandwich alongside the roasted potatoes, or allow to cool completely before storing in airtight containers for meal prep.