Heat oven to 350°F. Grease 9-inch springform pan.

In a food processor combine pretzels, brown sugar, cinnamon, and butter. If you don't have a food processor, put pretzels in a plastic storage bag and bang with a heavy object to make fine crumbs.

Combine the four ingredients in a bowl. Dump mixture into pan and press into bottom.

Bake for 7 minutes. Remove from oven.

In a large mixing bowl with paddle attachment, beat the cream cheese until creamy. Add sugar and beat until smooth.

On medium-low speed, beat in lime curd, sour cream and flour until smooth.

Stir in Key lime juice and vanilla.

With mixer on low speed, beat in eggs and egg yolk, one at a time, scraping down the sides after each one.

Pour half the filling into crust.

Drop teaspoons of blackberry jam randomly into filling, using three-fourths of jam. With a butter knife, gently swirl jam into batter without touching crust.

Pour second half of filling into pan and drop teaspoons of jam into the batter, swirling gently with butter knife.

Bake at 350°F for 1 hour or until lightly brown on top and center is just slightly jiggly.

Cool to room temperature. Chill in fridge for 24 hours. Serve with blackberries.

Store leftovers in refrigerator up to one week or in freezer up to three months.