Special equipment: a (3- to 4-inch) heart shaped cookie cutter
Preheat oven to 425°F with rack in middle.
Wrap each beet tightly in foil. Place on a baking sheet and roast until tender, 1 to 1 1/4 hours. Unwrap to cool.
While beets are cooling, whisk together shallot and lemon juice with 1/4 teaspoon each salt and pepper in a small bowl, then whisk in oil.
Once beets are cool enough to handle, peel off skins using a small sharp knife. Cut beets into 1/4 inch dice and transfer to a bowl. Add 2 tablespoons dressing to beets and stir to combine. Adjust seasoning if necessary.
Place half of greens on a salad plate. Place cookie cutter in center of plate on top of greens and put 1/4 of beets in cutter and pack down with your fingertips or the back of a teaspoon. Crumble half of goat cheese on top, then cover with another 1/4 of beets, packing them down once again. Gently lift cutter up and away from stack. Make another plate with remaining greens, beets, and goat cheese. Sprinkle almonds around plate and drizzle remaining dressing over and around greens.
Make ahead: Beets can be roasted and diced 1 day ahead and chilled, covered.