4 medium russet potatoes
1 cup peeled and cubed butternut squash
4 tbs unsalted butter
1/2 cup grated parmigiano reggiano
4-5 tbs skim milk
kosher salt to taste
Fill a large pot halfway with water and bring to a boil. Meanwhile, peel the potatoes and chop into uniform size cubes (about 1 inch). When the water comes to a boil add the potatoes and squash, cover, and boil on high for 10-15 minutes until fork tender.
Drain the potatoes and squash and put in a large bowl. Add the butter, parmigiano reggiano, and a dash of kosher salt. Using a potato masher, begin to mash the mixture together. As it starts to come together (about 1 minute) add a tbs of skim milk at a time until the mixture reaches the creamy consistency you like. Add kosher salt if needed and serve warm.