Boston Brown Bread

Bring 3 quarts water to simmer in large stockpot over high heat. Fold two 16 by 12-inch pieces of aluminum foil in half to yield two rectangles that measure 8 by 12 inches. Spray 4-inch circle in center of each rectangle with vegetable oil spray. Spray insides of two clean 28-ounce cans with vegetable oil spray.

Whisk rye flour, whole-wheat flour, cornmeal, baking soda, baking powder, and salt together in large bowl. Whisk buttermilk, molasses, and melted butter together in second bowl. Stir raisins into buttermilk mixture. Add buttermilk mixture to flour mixture and stir until combined and no dry flour remains. Evenly divide batter between cans. Wrap tops of cans tightly with prepared foil, positioning sprayed side of foil over can openings.

Place cans in stockpot (water should come about halfway up sides of cans). Cover pot and cook, maintaining gentle simmer, until skewer inserted in center of loaves comes out clean, about 2 hours. Check pot occasionally and add hot water as needed to maintain water level.

Using jar lifter, carefully transfer cans to wire rack set in rimmed baking sheet and let cool for 20 minutes. Slide loaves from cans onto rack and let cool completely, about 1 hour. Slice and serve. (Bread can be wrapped tightly in plastic wrap and stored at room temperature for up to 3 days or frozen for up to 2 weeks.)