This loaf cake boasts a marbled interior featuring one of our favorite flavor combinations—nutty, savory tahini and rich dark chocolate. The cake’s striking design is made by alternating layers of chocolate-enriched batter and plain, lightly colored batter, then using a butter knife to swirl the two together. A buttery chocolate-tahini glaze comes together quickly in the microwave and accentuates the cake’s flavors beautifully. Though we often prefer to use bittersweet chocolate in our sweets, for both the batter and glaze in this recipe we find that semi-sweet better complements the earthy, subtly bitter notes of the tahini. Dense and moist, this cake takes about 2 hours to cool completely. Applying the glaze about halfway through the cooling period ensures it is fully set by the time the cake is ready to serve. While the cake is best enjoyed the day it's made, it can be stored at room temperature in an airtight container or wrapped in plastic for up to two days.