Preheat Oven to 350° degrees. Line cookie sheets with silicone mats or parchment paper.
Using a stand mixer or hand mixer, cream the softened butter and sugar for about 2 minutes on high. The mixture will start to look fluffy and lighten in color.
In a small bowl, combine egg, vanilla, baking powder, and salt. Add this mixture to the butter and sugar, cream on medium speed until fully combined.
Measure out flour in a separate bowl. Add to the butter/egg mixture about ½ cup at a time and beat on low. Continue adding in ½ increments until all of the flour has been added.
At this point, the mixture will look slightly dry and crumby. Add the heavy cream and beat on high for 10-20 seconds. As soon as the dough starts to come together, stop beating. The sugar cookie dough will be very slightly tacky, but should not be sticky.
In between 2 sheets of wax paper, roll out about half of the dough to ⅜" to ½" thickness. Roll out the other half of the dough in 2 additional wax paper sheets.
With your cookie cutters, cut out the hearts and place them on a cookie sheet. Place the cookie sheet in the freezer for about 10-15 minutes. Make sure the dough is hard, but not frozen solid. Insert the lollipop stick through the bottom edge of the cookie until it reaches over halfway up the cookie.
Bake for 14-16 minutes until the bottom edges are golden brown. Remove the baking sheet from the oven and let the cookies cool on the pan for at least 10 minutes. Move to a cooling rack and let cool completely.