Preparation Steps

• Heat the oven to 355°F (180°C). Line an 8.5×4.5-inch loaf pan with a parchment sling, leaving overhang on the long sides, and lightly grease.
• In a medium bowl, whisk together the flour, baking powder, salt, and nutmeg; set aside.
• In a large mixing bowl (or stand mixer), beat the softened butter and granulated sugar on medium speed until light and fluffy, about 2 minutes. With the mixer running, stream in the oil and beat 30 seconds more.
• Beat in the eggs one at a time, then mix in the vanilla until smooth. Scrape the bowl and beater.
• Add half of the dry ingredients, mix on low just to combine, then pour in all the buttermilk. Finish with the remaining dry ingredients and mix just until no dry streaks remain. Let the batter rest 5 minutes to hydrate.
• Scoop 3/4 cup of batter into a small bowl and stir in the cinnamon, brown sugar, and maple syrup to make the ripple.
• Layer the loaf: spread one-third of the plain batter in the pan, dollop on half of the cinnamon ripple, add another third of plain batter, then the remaining ripple, and finish with the last third of plain batter. Drag a skewer through the loaf in two long S-shaped passes for a defined swirl (avoid over-mixing).
• Bake 42–48 minutes, until the top springs back and an instant-read thermometer in the center reads 203–205°F, or a toothpick comes out with a few moist crumbs.
• Cool in the pan for 12–15 minutes, then lift the loaf out onto a wire rack.
• For the coating, stir the granulated sugar, brown sugar, and cinnamon together in a shallow dish. Gently melt the butter until just liquid (not sizzling). Brush the warm loaf on all sides with melted butter, then roll and pat it in the cinnamon-sugar mixture until fully covered.
• Let the crust set for 10 minutes, then slice and serve warm or at room temperature.