Begin by slicing potatoes into roughly 1 inch cubes. Add to a large pot and cover with water. Add a pinch of salt and bring mixture to a boil. Reduce to a rapid simmer and let cook uncovered, until a fork stuck in the potatoes can poke through without resistance, but not so long that the potatoes fall apart. This typically takes about 2o minutes for my but can take longer (up to 40 minutes) if you use a different kind of potato or have them cut into larger cubes. Remove from heat and drain in a colander. If desired, let cool and slip the skins off each cube (I skip this step as I don't mind the skin). When finished, add potatoes back into the pot.

Heat olive oil/butter in a skillet over medium. Add leek and shallot and season with a large pinch of salt. Sauté for 5 minutes until mixture takes on a bit of color.

Add cabbage and stir to combine. Let cabbage cook to soften, a few minutes more. The cabbage should release some water. Add kale on top of cabbage and cover with a lid to steam for a couple of minutes to soften. Stir, add another pinch of salt and minced garlic and cook 30 seconds more. Remove from heat and set aside

Mash your potatoes with a masher or a large fork. Do not try blending them, as this can cause excess starch to release and make the potatoes "gummy." Add half of the milk and stir to check consistency. Potatoes drink up liquid quickly, so you'll likely want to add the rest of the milk to create a more creamy texture.

Add cabbage/kale mixture to pot of potatoes, stirring to combine. Top with black pepper and green onions to serve.