Preheat the oven to 350 degrees F. (You will turn the oven temperature down to 325 degrees F once you put the cakes in the oven.)
Grease and flour two 8" round cake pans. (If making cupcakes, read notes below)
Combine the flour, sugar, baking powder, baking soda and salt in a large mixing bowl and whisk well. Set aside.
In another bowl, combine the sour cream, milk, oil, vanilla bean paste, almond extract and eggs. Mix well with a whisk and set aside.
Cut the almost room-temperature butter into chunks. Turn the mixer on low and slowly add the butter, a bit at a time, to the dry ingredients. Once all the butter has been added, mix on medium to medium-high until all the flour is coated with the butter and the mixture is crumbly. It should have a sand-like texture. If the butter is too warm or if it's mixed for too long, it will form a paste and this will not produce a good cake texture. Pour about a third of the liquid mixture. into the dry mixture and mix on low to medium until well combined...about 30 seconds to one minute. (Some reverse creaming recipes call for mixing 1-2 minutes at this stage, but be careful about mixing longer than a minute as mixing for too long will cause a dense cake.)
Pour the last of the liquid mixture into the dry mixture and mix again until well combined. Don't overmix the batter at this point. Stop mixing once everything is well incorporated, usually no more than about 20-30 seconds.
Use a silicone spatula to scrape down the sides and bottom of the bowl. Mix again for only about 10 to 15 seconds.
Pour the cake batter into the prepared pans.
Slide the cake pans into the oven and turn the oven temp down to 325 degrees F (unless you're making these as cupcakes, in which case you'll want to read the notes below).
Bake at 325 degrees F for approximately 40-45 minutes. The cakes are done when a toothpick inserted into the center of each layer comes out with a few moist crumbs on it or clean, but no raw batter.
Set on wire racks to cool for ten minutes, then turn the cakes out onto the racks and let them cool out of the pans completely before adding buttercream frosting.