One in an occasional series of essential household tools: A white (non-marking) rubber mallet. Whether it’s assembling a rocking horse, fitting shelves into a bookcase, or flattening chicken breasts for Poached Chicken Breast Stuffed with Goat Cheese and Spinach (cover the chicken in plastic wrap first), this is a tool you never knew you needed that you’ll use all the time. Gentler than a metal hammer, but still with heft behind it.