I'm trying to make a cherry cream pie and have seen the following recipe
for this cream filling many times on the internet.

1 can (15 ounce; 1 1/3 cups) sweetened condensed milk
1/3 cup lemon juice
1 teaspoon vanilla
1/2 teaspoon almond extract
1/2 cup whipping cream; whipped
Combine sweetened condensed milk, lemon juice, vanilla and almond
extract.
Stir until mixture thickens. Fold in whipped cream

I can not get this stuff thick enough to support a layer of pie filling.
I've stirred and stirred with no effect. I even tried cooking it and
that was too satisfactory either. Any ideas?

Larry