What kind of squash should I use?
Delicata is my favorite here because the skin is edible and it roasts fast. Acorn works great too. For butternut, peel and cut into 1-inch chunks. For kabocha, the skin is edible but can be tough depending on the squash, so I often peel it for this (or roast it skin-on and just know you might get a chewier bite).
Do I have to use whole peppercorns?
Whole peppercorns cracked fresh give you that bold, floral pepper bite without tasting dusty. If you only have pre-ground pepper, use it. Start with 3/4 to 1 teaspoon and adjust to taste.
How do I crack peppercorns without a grinder?
Put peppercorns in a zip-top bag and lightly smash with the bottom of a skillet or a rolling pin. You want coarse pieces, not powder.
Why is my squash not browning?
Usually one of three things: the pan is crowded, the oven is not hot enough, or the squash is too wet. Spread it out in a single layer, roast at 425°F, and pat pieces dry if they seem damp.
Can I make this ahead?
Yes. Roast the squash up to a day ahead, refrigerate, then reheat in the oven. Store the sauce separately and rewarm it gently over low heat so it stays glossy. If it looks like it wants to split, pull it off the heat and whisk in a teaspoon of water.