Begin by spreading butter evenly on both slices of the bread.
Heat a large cast iron skillet over medium heat, toast bread on both sides and set aside, about 2-4 minutes on each side.
Add the softened mascarpone, lemon juice, and zest to a mixing bowl and mix until combined.
Use a knife or spatula to spread each piece of toasted bread with a generous amount of the mascarpone mixture.
For Savory Toast: Add olive oil, Italian seasoning, and salt into a large bowl and whisk to combine. Then, add the sliced tomatoes. Spoon the oil mixture over the tomatoes. Top the mascarpone with tomatoes and sprinkle with feta cheese. Sprinkle with salt, pepper, and drizzle the remaining olive oil from the tomatoes over the toast.
For Sweet Toast: Spread jam on top of the mascarpone and then top with fresh berries. Finally, drizzle on honey, to taste.