Prepare the Crust

1. Preheat oven to 325°F (160°C).
2. In a food processor, pulse Ritz crackers until finely chopped.
3. In a medium bowl, combine cracker crumbs with melted butter, mixing until well combined.
4. Press mixture into the bottom and 1 inch up the sides of a 9-inch springform pan.
5. Bake crust for 10 minutes, then set aside to cool.

Cook the Sausage and Crawfish

1. Heat a medium skillet over medium-high heat, adding sliced andouille sausage.
2. Cook for about 5 minutes, until lightly browned.
3. Add crawfish tail meat and chopped jalapeño to the skillet, cooking until the jalapeño softens, about 3 minutes.
4. Remove from heat and let mixture cool.

Prepare the Cheesecake Filling

1. In a large bowl, beat softened cream cheese and sour cream on medium speed until smooth.
2. Gradually add cooled sausage and crawfish mixture, thyme, salt, and black pepper, folding until evenly combined.
3. Add eggs one at a time, beating just until each one is incorporated to avoid over-mixing.

Assemble and Bake the Cheesecake

1. Pour cream cheese mixture over prepared crust in the springform pan.
2. Place springform pan in a larger roasting pan and fill with hot water until it reaches halfway up the sides.
3. Bake for about 1 hour, or until cheesecake is set but has a slight jiggle in the center.
4. Remove from oven and cool completely on a wire rack.
5. Cover and refrigerate cheesecake for at least 4 hours or up to 3 days before serving.

Crawfish Beurre Blanc Sauce

1. In a medium skillet over medium-high heat, add vegetable oil.
2. Stir in crawfish, shallot, and ½ teaspoon kosher salt; cook until shallot is tender, about 3 minutes. Set aside to cool.
3. In a medium saucepan over medium-high heat, combine dry white wine, white wine vinegar, hot sauce, thyme sprigs, peppercorns, and garlic. Simmer until reduced by one-third, about 15 minutes.
4. Strain liquid through a fine mesh strainer, discarding solids. Return liquid to saucepan.
5. Add heavy cream, cooking until mixture thickens enough to coat the back of a spoon, about 10 minutes.
6. Reduce heat to medium-low. Gradually add cubed butter, stirring until melted and sauce is smooth.
7. Stir in remaining ½ teaspoon salt and the sautéed crawfish mixture. Serve sauce immediately over slices of Crawfish Cheesecake.