Mashed Potato Cake with Caramelized Onions and Sage Buttercream
This surprisingly easy-to-make savory 'cake' defies expectations while embracing the flavors of mashed potatoes and gravy.
Ingredients
Mashed potatoes:
- 4 pounds potatoes Yukon Gold peeled, quartered
- 8 tablespoons butter
- 3/4 cup heavy cream
- 3/4 teaspoon kosher salt
- 1/8 teaspoon black pepper
- 1/2 cup Parmesan cheese grated
Onion jam:
- 3 large onions thinly sliced
- 2 tablespoons butter
- 1 tablespoon olive oil
- 1/2 teaspoon salt
- 1 teaspoon thyme
- 1 teaspoon sherry vinegar
- 1 teaspoon brown sugar
Sage 'buttercream':
- 24 ounces cream cheese room temp
- 1 cup sour cream
- 8 tablespoons browned butter
- 1 teaspoon ground sage
- 1 teaspoon salt
- 1/4 teaspoon black pepper
Serve with:
- Pan Gravy on the side
Instructions
Mashed potatoes:
- Boil potatoes in salted water until tender; drain and steam dry.
- If you have a potato ricer, rice the potatoes; or mash; with butter, warm milk, salt/pepper, and Parmesan to spreadable but firm consistency. Cool until just warm.
Onion jam:
- Slowly caramelize onions in butter and oil with salt and thyme (30-45 minutes). Deglaze with a splash of vinegar; stir in brown sugar; cook until jammy.
Sage 'buttercream':
- In small saucepan over medium heat, brown 4 Tbsp butter. Add ground sage.
- Beat cream cheese and sour cream smooth; stream in warm brown butter; season.
Build cake:
- Line a 9-inch springform with parchment paper/ Spray with non-stick cooking spray.
- Press half the mashed potatoes into an even layer.
- Spread onion jam.
- Top with remaining mashed potatoes; smooth.
- Chill 20 minutes to set.
- Unmold springform pan. Place serving platter on top of open pan, then flip cake (upside down) onto a platter. Carefully peel off parchment paper.
- Frost sides and top with 'buttercream' like a cake. You will have enough frosting to also pipe decorations, if desired.
- Garnish with crispy shallots and cracked pepper.
- Warm gently (275°F, 15-20 minutes) before serving, or serve room temp.