For the roasted garlic and tomato hollandaise: Preheat the oven to 375 degrees F.
Toss the tomatoes and garlic with the oil in a medium bowl and season with salt and pepper. Put on a baking sheet and roast until the tomatoes and garlic are soft and the liquid has evaporated, about 30 minutes. Let cool slightly.
Combine the egg yolks and lemon juice in a blender and blend until smooth. With the motor running, slowly add the melted butter and continue blending until emulsified. Add the tomato-garlic mixture and blend until smooth. Cover and keep warm.
For the sandwiches: Heat the oil in a large cast-iron skillet over medium heat until it begins to shimmer, about 2 minutes. Add the Canadian bacon and cook, turning once, until heated through and lightly browned, about 2 minutes per side. Remove to a small plate and keep warm. Keep the fat in the skillet and the heat at medium.
While the bacon cooks, use a 2-inch round cutter to cut a hole out of the center of each bottom half of the muffins (the bottom is the larger half, usually with cornmeal stuck to it). Melt some of the butter in the skillet until foaming and add the 4 halves of the muffins with the holes, cut-side down. Crack an egg into each hole (it's OK if the egg runs over the muffin), season with salt and pepper, and cook undisturbed until the bottoms are golden brown, about 3 minutes.
Using a flat spatula, flip the muffins and cook until the second side is golden brown, about 2 minutes for runny yolks. Put the bacon on top after the first minute or so. Remove to a work surface, keeping the bacon sides up. Quickly add the remaining butter to the skillet and add the muffin tops cut-side down to toast.
Spoon about 1 1/2 tablespoons of the warm hollandaise on top of each egg, then top with a toasted muffin top. Serve immediately.