1/2 cup unsalted butter (1 stick), browned
2 large eggs
1/3 cup buttermilk
1 cup granulated sugar
1/4 cup light brown sugar, packed
2 teaspoons vanilla extract
1 teaspoon ground cinnamon
1 cup mashed bananas (about 2 large ripe bananas)
1 3/4 cup all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
pinch salt, optional and to taste
2 tablespoons unsalted butter, well softened
2 to 4 tablespoons strawberry preserves (or another favorite jam, jelly, or preserves)
Bread - Preheat oven to 350F. Spray two 8-by-4-inch loaf pans with floured cooking spray; set aside. Bread may be baked in one 9-by-5-inch pan at your own risk; or bake as muffins, mini loaves, or in a Bundt pan, adjusting baking times accordingly.
In a heavy-bottomed large pot or skillet, melt 1/2 cup butter over medium-low heat, stirring nearly continuously or swirling the pan. Butter will melt, foam, turn clear, golden, turn brown, and will then smell nutty. As soon at the butter begins to turn brown, take the pan off the heat, and continue to stir for about 1 minute, to ensure carryover heat doesn't continue to cook and subsequently burn the already browned butter. Pour butter in large mixing bowl.
To the butter, add the eggs, buttermilk, sugars, vanilla, cinnamon, and whisk to combine.
Add the bananas and stir to incorporate. Increasing mashed bananas to 1 1/2 cups and also increasing flour to 2 cups is optional if you prefer more intensely banana-flavored banana bread.
Add the flour, baking power, baking soda, optional salt (buttermilk is already salted, and if using salted butter, and then adding salt, bread could become too salty so use caution here), and stir until just combined, taking care not to over-mix or bread will be tougher as the gluten will over-develop.
Turn batter out into prepared pans, smooth tops lightly with a spatula, and bake for 35 to 42 minutes (I baked 37 mins for 1 loaf, 40 mins for the other), or until top is golden and set, and a wooden skewer, cake tester, or knife inserted in the center comes out mostly clean (banana bread is gooey and it won't come out perfectly clean). If bread is browning too fast on the top, you may wish to lower your oven temperature to 325F in the second half of cooking or tent the pan with foil although I don't suspect this will be an issue.
Allow bread to cool in pan for at least 10 minutes before removing and transferring to a rack to finish cooling. Bread will keep for up to 1 week airtight at room temperature (I wrap my fully cooled bread in plasticwrap, then I place it in a gallon-sized Ziplock). Second loaf may be frozen for up to 6 months.
Strawberry Butter - Combine 2 to 4 tablespoons butter with preserves and whip vigorously until combined and fluffed. The softer the butter is, the easier it will be to whip. Quantity may be doubled, tripled, etc. based on need. Store strawberry-butter in an airtight container in the refrigerator for up to 2 weeks.