Directions

• For the pastry cream
• Line a plate with plastic wrap, making sure the sides are covered. Set aside.
• Pour 1 ½ cup milk into a medium sized heavy bottomed saucepot. Add 2 tablespoons of sugar. Whisk and place over medium-high heat. Bring to a boil. Stir occasionally to ensure milk does not burn along sides or bottom of the pot.
• Meanwhile, in a medium bowl, whisk together cornstarch and remaining sugar. Add yolks and remaining ½ cup of milk. Whisk together until smooth. 
• Once milk has come to a boil, reduce heat. Slowly add about ¼ cup of hot milk into egg mixture. Immediately whisk to distribute heat. Continue to add small portions of the hot milk into the egg mixture, whisking to distribute heat. Do this until only a few tablespoons of milk remain in the saucepot. 
• Pour all of the egg-milk mixture back into the saucepot. Set pot over medium heat. Stir constantly until mixture thickens. Keep stirring and let the custard come to a boil for 20-30 seconds to cook out unwanted cornstarch flavor. Remove from heat.
  Stir in butter and salt until melted and incorporated. Next, add vanilla and stir to combine.
• Immediately pour the hot pastry cream into the prepared plastic wrapped plate. Spread evenly. Cover pastry cream with plastic wrap, allowing wrap to touch surface of pastry cream. Freeze for 10-15 minutes to quickly cool pastry cream. Remove from freezer and continue to cool in refrigerator until ready to use. 
• For the cake
• Preheat oven to 350°F. Grease a round 10-inch cake pan and line bottom and sides of the pan with parchment paper. Grease the parchment paper and set aside.
• In the bowl of a stand mixer fitted with a paddle attachment, cream together softened butter and sugar until smooth. Scrape down bowl as needed to ensure thorough mixing.
• Add vanilla and glycerin. With the mixer running on medium speed, add eggs one at a time. Ensure each egg is incorporated into batter before adding the next. Scrape down sides of bowl.
• In a medium bowl, whisk together flour, baking powder, and salt. Add half of flour mixture to mixing bowl. Mix on the lowest speed until almost combined. Add remaining flour mixture and mix on low until there are no longer and dry streaks of flour.
• Transfer half of batter to a piping bag fitted with a 15mm round tip. Pipe a spiral of cake batter into prepared cake pan, covering the bottom of cake pan. Use the back of a spoon or a mini offset spatula to smooth out the batter or cover any gaps, if necessary.
• Pipe a ring of batter along the edges of cake to create a border. Spread strawberry jam within boundaries of cake batter ring.
• Refresh pastry cream by giving it a good whisk. Spread pastry cream in an even layer over strawberry jam.
• Fill piping bag with remaining cake batter. Once again, pipe a spiral of cake batter. Make sure to completely cover and encase the pastry cream. Use the back of a spoon or a mini offset spatula to smooth out batter or cover any gaps, if necessary. You will use up every last bit of cake batter.
• Bake for 50-60 minutes until top of cake is golden brown, the edges of the cake are set and are beginning to pull away from the pan, and most importantly, the center of cake no longer jiggles.
• Allow cake to cool in pan for 20-30 minutes. Run a dull knife or mini offset along the perimeter of cake to loosen from pan. Invert and unmold cake. Turn cake upright and place on a wire rack. Allow cake to completely cool to room temperature, about 2-3 hours.