Bring butter, eggs, and sour cream to room temperature.

In medium-sized bowl, sieve or sift the dry ingredients.

Chop the dates and nuts and combine with the raisins and dried cranberries in small bowl.

In bowl of stand mixer fitted with paddle attachment, cream the butter at medium-high speed until smooth and creamy. With mixer set at low speed, gradually add the brown sugar then beat on medium speed for 1-2 minutes, stopping to scrape down sides of bowl, if and as necessary. Mix in eggs, one at a time, beating to incorporate after each addition. Add the sour cream and vanilla and beat just to incorporate. Do not overbeat mixture.

With speed of mixer set to low, gradually add the dry ingredients and beat mixture just until ingredients are combined. Remove bowl from mixer stand and mix in the dates, raisins, cranberries, and nuts.

Cover bowl tightly and refrigerate for at least 1½ - 2 hours to firm up butter content in dough. Dough may be refrigerated for up to 48 hours before baking.

To bake, remove cookie dough from refrigerator and, if necessary for dough to be scooped up, let sit at room temperature for about 10-15 minutes, or until dough is just pliable enough to be scooped up by tablespoonfuls to form cookies. Do not let cookie dough completely soften at room temperature as this will soften the butter in the dough and may cause cookies to spread and bake flat.

Position oven rack in center of oven and preheat oven to 350°F. Line baking sheet(s) with parchment paper.

Scoop up dough by rounded tablespoonfuls and transfer to prepared baking sheet, spacing cookies 2” apart. Bake for 14-17 minutes (depending on size of cookies), or until cookies have puffed up, have the appearance of the tops starting to look dry, edges set, and the cookies are tanned. Rotate cookie sheet(s) at the halfway point during baking. To maintain a soft and chewy texture, do not overbake cookies. Remove cookies from oven and let rest on cookie sheet for 3-4 minutes before transferring to wire rack to cool.