Step 1
Mash 3 cups sliced strawberries with 1 cup sugar in a saucepan over medium heat. Bring strawberry mixture to a boil stirring frequently.
Step 2
Mix cornstarch with water in a small bowl and pour into mashed strawberries; reduce heat to medium-low.
Step 3
Let strawberry mixture simmer stirring constantly until thickened about 10 minutes. Set aside.
Step 4
Bring half-and-half to a boil in a saucepan; remove from heat.
Step 5
Beat egg and egg yolk with an electric mixer in a bowl until frothy; gradually mix in 3/4 cup of sugar then beat until the egg mixture is thick pale yellow and forms a ribbon when beater is lifted out of the bowl about 3 minutes.
Step 6
Mix in flour until smooth.
Step 7
Gradually pour hot half-and-half into the egg mixture in a steady stream beating constantly.
Step 8
Return mixture to the saucepan and place over medium heat. Cook stirring constantly with a wooden spoon until the custard thickens and starts to boil. Reduce heat to medium-low; continue cooking stirring constantly until flour is cooked 2 to 3 more minutes.
Step 9
Remove custard from heat and stir in butter and vanilla extract.
Step 9
Spread custard in an even layer over the bottom of graham cracker crust. Top the custard with the cooked strawberry mixture. Arrange fresh strawberries over the top.