Apple Cider Doughnut Loaf

In a large saucepan, bring cider to a boil over medium-high heat; cook, stirring occasionally, until reduced to ¾ cup (205 grams), 45 minutes to 1 hour. Remove from heat, and let cool completely.

Preheat oven to 350°F (180°C). Spray an 8½x4½-inch loaf pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides of pan.

In a large bowl, whisk together ⅔ cup (133 grams) sugar, applesauce, oil, egg, and vanilla.

In a medium bowl, whisk together flour, 1 tablespoon (6 grams) cinnamon, baking powder, salt, and baking soda. Gradually add flour mixture to sugar mixture alternately with reduced cider, beginning and ending with flour mixture, whisking until just combined after each addition. Spread batter into prepared pan.

Spoon butter into a pastry bag, and cut a ¼-inch opening in tip. Pipe butter in a line down center of batter.

In a small bowl, whisk together remaining 2 tablespoons (24 grams) sugar and remaining ½ teaspoon (1 gram) cinnamon; sprinkle onto batter.

Bake until a wooden pick inserted in center comes out with a few moist crumbs, 50 minutes to 1 hour. Let cool in pan on a wire rack for 10 minutes. Using excess parchment as handles, remove from pan, and let cool completely on a wire rack. Store in an airtight container for up to 3 days.