In a medium saucepot, combine potatoes, rosemary sprigs, a pinch of kosher salt and cover with water by one inch. Over high heat, bring to a boil, and remove both rosemary sprigs with a kitchen fork. Turn heat down to medium, and simmer until potatoes
are tender and cooked through.

While potatoes are cooking, heat a medium-large sauté pan over medium-high heat, add the olive oil and half of butter. When the butter has melted, add onion and garlic and cook for 3-4 minutes until lightly browned. Add the mushrooms and cook for another
3-4 minutes or until cooked. Add the tomato and cook for another 1-2 minutes. Add the flour and cook for two more minutes while stirring to combine. Add 1/4 cup of water, a pinch of salt and pepper and bring to a boil. Turn down heat to low and simmer
for 8-10 minutes.

While the mushrooms are cooking, drain the potatoes in a colander and put them back in the pot they cooked in. Add rosemary sea salt, remaining butter and smash with a potato masher or kitchen spoon until fully incorporated.

When the mushrooms have cooked, remove from heat, and season to taste with salt and pepper. Add fresh parsley. Divide the potatoes onto two plates, top with mushrooms. Serve and enjoy!