Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.

In a large bowl, whisk together flour, granulated sugar, baking powder, optional salt; set aside.

In a separate small bowl, whisk together the egg, buttermilk, sour cream, oil, and vanilla.

Add the wet mixture to the dry, mixing lightly with a spoon or folding with a spatula until just combined. Small lumps will be present, don’t overmix or try to stir them smooth.

Turn batter out into prepared pan and bake for about 29 to 32 minutes, or until center is set and not jiggly, and a toothpick inserted in the center comes out clean or with a few moist crumbs, but no batter.

Place pan on a wire rack and allow cake to cool. While cake cools, make the glaze.

Cook butter over medium-high heat in a small saucepan until it’s amber to brown in color, about 5 minutes depending on pan size, but watch it closely so you don’t burn it.

Transfer butter, including brown bits at the bottom of the pan to a large mixing bowl to stop any carryover cooking.

Add the confectioners’ sugar, vanilla bean paste, optional salt, and slowly add the milk, whisking until smooth or beat with a handheld electric mixer.

As necessary, add additional cream (or confectioners’ sugar) to reach desired glaze consistency. Glaze should be of medium thickness and easily pourable.

Evenly pour glaze over cake (doesn’t have to be fully cooled), smoothing it lightly with a spatula if necessary.

Allow cake to cool in pan uncovered for at least 2 hours (or overnight and cover with a sheet of foil) before slicing and serving so glaze can set up.

Cake will keep airtight at room temperature for up to 5 days, or in the freezer for up to 6 months.