Preheat the oven to 350°F (177°C). In a medium bowl, whisk together the flour, baking powder, and salt. Whisk to combine. Set aside.
In a small bowl, add the sugar and lemon zest. Rub the sugar and zest with your fingers until the sugar is fragrant -- about 30 seconds.
In a standing mixer outfitted with the paddle attachment (or in any large bowl if using electric beaters), beat the butter and lemon-sugar together at medium-high speed until light and fluffy. Then add the eggs one at a time, beating well after each addition. Beat in the sour cream and lemon extract.
At low speed, gradually beat in the flour. Beat only the flour disappears into the battle. Scrape down the sides and bottom of the bowl to insure that all ingredients are thoroughly combined.
Lightly spray the openings of the bundtlette pan with vegetable spray.
Bake in the preheated oven until the cakes are done -- usually 20-25 minutes. Knock out the cakes onto a wire rack, and let them cool to room temperature.