Preheat the oven to 350°F (175°C). Line an 8-inch square baking pan with parchment paper and lightly grease it.
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, beat the softened unsalted butter and granulated sugar together with an electric mixer on medium speed until light and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition.
Mix in the sour cream, fresh lemon juice, lemon zest, and vanilla extract until combined.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Pour the batter into the prepared baking pan and spread evenly.
Bake for 22 to 25 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and allow the cake to cool completely in the pan on a wire rack.
Once cooled, crumble the cake into a large bowl using your hands or a fork until fine crumbs form.
Melt 2 ounces of white chocolate candy melts in a microwave-safe bowl in 30-second intervals, stirring between each, until smooth.
Add the melted white chocolate to the cake crumbs and mix thoroughly until the mixture holds together when pressed.
Roll the mixture into 24 equal-sized balls, about 1 inch in diameter, and place them on a baking sheet lined with parchment paper.
Insert a white lollipop stick halfway into each cake ball, then refrigerate the cake pops for at least 1 hour to firm up.
Melt the remaining 6 ounces of white chocolate candy melts in a microwave-safe bowl in 30-second intervals, stirring until smooth.
Dip each chilled cake pop into the melted white chocolate, allowing the excess to drip off.
Immediately decorate with colorful sprinkles before the coating sets.
Place the decorated cake pops upright in a styrofoam block or a cake pop stand to dry completely, about 30 minutes.
Once set, the lemon cake pops are ready to serve.