Sous Vide Lemon Cheesecake Cups

 FOR THE TOPPING: Pulse cracker pieces in food processor to fine crumbs, about 15 pulses. Melt butter in 10-inch nonstick skillet over medium-low heat. Stir in sugar, cinnamon, salt, and crumbs. Cook, stirring frequently, until fragrant, about 1 minute; transfer topping to small bowl and let cool. (Topping can be stored at room temperature for up to 5 days.) Wipe processor bowl and blade to remove any crumbs.

 FOR THE FILLING: Using sous vide circulator, bring water to 176°F/80°C in 7-quart container. Process sugar and lemon zest in now-empty processor until sugar is pale yellow, about 30 seconds, scraping down sides of bowl as needed. Add cream cheese and process until smooth, about 30 seconds, scraping down sides of bowl as needed. Add eggs, cream, vanilla, salt, and lemon juice and process until just incorporated, about 15 seconds, scraping down sides of bowl as needed. Strain mixture through fine-mesh strainer into 4-cup liquid measuring cup, then divide evenly among eight 4-ounce Mason jars. Gently tap jars on counter to remove any air bubbles, then seal (do not overtighten lids).

 FOR THE LEMON CURD: Whisk egg and yolk together in medium bowl. Combine sugar, lemon juice, butter, and salt in small bowl and microwave until butter and sugar are melted, 45 to 60 seconds, whisking halfway through microwaving. Slowly pour half of lemon mixture into eggs, whisking constantly until smooth. Whisk remaining lemon mixture into eggs. Stir in cream and vanilla. Strain through fine-mesh strainer into 8-ounce Mason jar. Seal; do not overtighten lid.

 TO COOK: Gently lower all 9 jars into water bath until fully submerged. Cover and cook for at least 1 hour or up to 1¼ hours. Transfer jars to wire rack and tighten lid rings. Wrap jar of lemon curd in dish towel and shake vigorously for 15 seconds to recombine contents. Let jars cool completely, about 1 hour. Refrigerate until chilled, at least 4 hours or up to 5 days.

 TO SERVE: Remove lids from cheesecake cups and let sit at room temperature for 20 minutes. Spoon 1 tablespoon lemon curd over top of each cheesecake and smooth with back of spoon. Sprinkle topping over curd and serve.