Pecan Topping:

• Butter or cooking spray, for the pan
• 1/2 cup packed light or dark brown sugar
• 8 tablespoons (1 stick) unsalted butter, cut into 1-inch pieces
• 1/4 cup honey or light corn syrup
• 1/8 teaspoon kosher salt
• 1 1/4 cups raw pecan halves (about 5 ounces), coarsely chopped

Cake:

• 3/4 cup sour cream or plain full-fat Greek yogurt, at room temperature
• 2 large eggs, at room temperature
• 1 1/2 cups all-purpose flour
• 1 1/2 teaspoons baking powder
• 1/2 teaspoon baking soda
• 3/4 cup granulated sugar
• 1/2 cup neutral oil, such as grapeseed, vegetable, or canola
• 1/4 cup water
• 1 teaspoon vanilla extract or paste
• 1/4 cup light or dark brown sugar
• 1/2 teaspoon kosher salt
• 2 teaspoons ground cinnamon
• Flaky salt, for sprinkling (optional)
• Vanilla ice cream, for serving (optional)