📖 Instructions

1. Get Started: First things first, peel and quarter the potatoes. Place them in a large pot and cover with cold, generously salted water. Bring to a boil over medium-high heat, then reduce the heat and simmer until the potatoes are fork-tender – about 15-20 minutes. Nobody likes crunchy potatoes in their knish!
2. Mash 'Em Good: Drain the potatoes well and return them to the pot. Use a potato ricer or a masher to mash them until they are smooth and lump-free. A ricer really makes a difference here, giving you that perfect texture.
3. Cheese, Please!: Add the softened cream cheese, shredded cheddar cheese, melted butter (or vegan butter!), salt, and pepper to the mashed potatoes. Mix everything together until well combined and creamy. Taste and adjust seasonings as needed – maybe a pinch of garlic powder? It's all about what tickles your taste buds.
4. Cool It Down: Transfer the potato and cheese mixture to a bowl and let it cool slightly. This will make it easier to handle when forming the knishes. I usually pop mine in the fridge for about 15 minutes.
5. Dough Time: While the potato mixture cools, prepare the dough. In a large mixing bowl, whisk together the flour, salt, and baking powder. Cut in the cold butter (or vegan butter!) using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Work quickly so the butter stays cold!
6. Mix the Dough: Gradually add the cold sour cream (or vegan sour cream!) to the flour mixture, mixing until a dough just comes together. Be careful not to overmix – you want a tender dough, not a tough one. If the dough seems too dry, add a teaspoon of ice water at a time until it comes together.
7. Chill Out, Dough: Wrap the dough in plastic wrap and chill in the refrigerator for at least 30 minutes. This allows the gluten to relax and makes the dough easier to roll out.
8. Roll and Cut: On a lightly floured surface, roll out the dough to about 1/8-inch thickness. Use a 3-inch round cookie cutter or a knife to cut out circles.
9. Fill 'Em Up: Place a spoonful of the potato and cheese mixture in the center of each dough circle. Bring the edges of the dough up and pinch them together to form a dumpling. Make sure to seal them well so the filling doesn't leak out during baking. They should look like cute little pouches.
10. Bake Time: Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper. Place the knishes on the prepared baking sheet, leaving some space between them.
11. Egg Wash (Optional): In a small bowl, whisk together the egg and a tablespoon of water to make an egg wash. Brush the tops of the knishes with the egg wash for a golden-brown finish. If you're going vegan, you can skip this step or use a plant-based milk wash instead.
12. Bake Until Golden: Bake the knishes for 20-25 minutes, or until they are golden brown and heated through. Keep an eye on them – ovens can be quirky!
13. Serve with Mustard: Let the knishes cool slightly before serving. Serve them warm with your favorite mustard for dipping. I'm partial to a good stone-ground mustard, but dijon is also a winner. Enjoy!
14. Mustard Drizzle (Optional): For an extra touch, whisk together some mustard with a little maple syrup or honey for a sweet and tangy drizzle.