- In small bowl, whisk together ½ cup milk and cornstarch until smooth. Set aside.
- In small saucepan set over medium heat, heat remaining milk just until simmering. Set aside.
- To make caramel for custard, stir brown sugar and water together in heavy saucepan set over medium heat until all sugar dissolves. Increase heat to high and cook without stirring until an instant-read thermometer reads between 210 and 215 degrees.
- Place egg yolks and pumpkin purée in large heatproof bowl and whisk. Gradually whisk in hot milk, then add cornstarch mixture. Slowly pour caramel into bowl while whisking to combine.
- Have large heatproof pitcher ready. Return custard to saucepan. Cook over medium heat, whisking constantly, until custard thickens, approximately 3–5 minutes, and an instant-read thermometer registers 175 degrees. Consistency should be similar to thick pudding. Remove from heat. Whisk in butter, vanilla, rum, and salt. Pour into heatproof pitcher.
- Pour ½ cup custard into 4 prepared jars. Cover with plastic wrap and chill until set, approximately 3–5 hours.
- Add 2 tablespoons Salted Caramel Sauce to each custard jar and then top with Cinnamon Cream.
Salted Caramel Sauce
- Pour cream into small pitcher. Scrape vanilla seeds and add bean pod and seeds to pitcher. Set aside.
- Place sugar in medium heavy-bottomed saucepan. Over medium heat, stir constantly and vigorously with wooden spoon. Once sugar has completely melted and turned amber in color, add butter pieces one at a time. Whisk until butter has completely melted before adding another piece. Whisk for approximately 3 seconds, then slowly pour vanilla cream into pot. Whisk until smooth. Add salt and whisk to combine. Strain into heatproof bowl and let cool slightly. Reserve.
- In mixing bowl combine all ingredients and whip until stiff peaks emerge.