Sweet Potato & Sage-Butter Casserole

2 lbs sweet potatoes, peeled and cut into 1-inch pieces
1 lb Yukon gold potatoes, peeled and cut into 1-inch pieces
1 stick unsalted butter, plus 2 Tbs, melted
2 1/2 Tbs chopped fresh sage
1 1/2 cups whole milk, warmed
coarse salt and freshly ground pepper
1 cup fresh breadcrumbs (from 3 slices white bread, crusts removed)

1) Place sweet potatoes and potatoes in a large saucepan; cover with water, and season with salt. Bring to a boil; reduce heat, and simmer until potatoes are tender, about 9 minutes. Drain; pass through a ricer into a bowl.
2) Preheat oven to 375 degrees. Melt 1 stick butter in a small saucepan over medium heat, swirling occasionally, until golden brown, 5 to 7 minutes. Remove from heat; add 2 tablespoons sage. Stir butter mixture and milk into potatoes. Season with salt and pepper. Transfer to a 2-quart casserole dish. (Mixture can be refrigerated for up to 2 days.)
3) Combine breadcrumbs with 2 tablespoons melted butter and remaining 1/2 tablespoon sage. Season with salt and pepper. Toss to combine.
4) Top potato mixture with breadcrumbs. Bake, uncovered, until bubbling around edges and breadcrumbs are golden brown, 30 to 40 minutes. (If browning too quickly, tent with foil.) Let stand, uncovered, for 10 minutes.

Review: I hadn't fully read the instructions when I chose this dish.  I didn't want a main meal of fancy mashed potatoes, so I left them cubed.  (And, I used yams instead of sweet potatoes, as the grocery store was out of sweet potatoes)  Unfortunately, that ended up meaning I had way too much butter for the potatoes.  If they had been pureed, I think it would have blended evenly.  Either way, it was still incredibly yummy.  This would make a really yummy, savory Thanksgiving side dish!