Cookies-

Preheat oven to 350 F. Line 2 rimmed baking sheets with parchment paper and set aside.

In the bowl of a stand mixer fitted with a paddle, mix together the butter, oil, sugars, baking soda, cream of tartar, and salt. Mix till very creamy, about 2-3 minutes. Scrape down the side of the bowl at least 2 times during this process.

Add the sour cream, eggs, and vanilla and mix another minute or 2, till well combined. Scrape the sides down as needed.

Pour the flour into bowl and mix on low till flour is incorporated and then mix on medium speed till well combined, scraping down the sides as needed. Dough will be soft. You don’t want the dough to be a normal sugar cookie consistency or these cookies won’t end up soft.

Pour about ½ cup of sugar in a small bowl.

Roll dough into balls *see note* and place a few inches apart on prepare rimmed baking sheet.

Using the bottom of a glass cup, twist the bottom of the glass in the bowl of cookie dough to get the glass a bit greasy and then dip it in the sugar. Press the bottom of the glass into a ball of dough on the cookie sheet till cookie flattens to about ½ inch and maybe gets a few crackles around the edges. Dip glass in sugar between each press of a dough ball (no need to re-twist in the bowl of cookie dough) until the whole tray is pressed.

Bake for about 8-10 minutes for large/normal size cookies or about 7 for a smaller one. Try to take them out right before the edges would start to brown or they will be too dry and not soft. They may look undercooked in the middle at first.

Let rest on baking sheet for about 3 minutes before transferring to a cooling rack.

Frosting-

In a bowl of a stand mixer fitted with a whisk attachment (or in a mixing bowl with an electric mixer) whip the cream cheese till creamy. Add the whipping cream and vanilla extract and whip till soft peaks. Add the sifted powdered sugar and whip till stiff peaks.